EPA 440/1-74/015
           DEVELOPMENT DOCUMENT FOR
       PROPOSED BEST TECHNOLOGY AVAILABLE
                       FOR
   MINIMIZING ADVERSE ENVIRONMENTAL  IMPACT  OF
    COOLING WATER INTAKE STRUCTURES
                           \
                    5SS2
          UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

                    DECEMBER 1973

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                         Publication Notice
This a development document for proposed effluent limitations
guidelines and new source performance standards.  As such, this report
is subject to changes resulting from comments received during the period
of public comments of the proposed regulations.  This document in its
final form will be published at the time the regulations for this
industry are promulgated.

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              DEVELOPMENT DOCUMENT

                      for

                    PROPOSED
           BEST TECHNOLOGY AVAILABLE

                      for
    MINIMIZING ADVERSE ENVIPONMENTAL IMPACT
       OF COOLING WATER INTAKE STRUCTURES
                Russell E. Train
                 Administrator

              Dr. Robert L. Sansom
Assistant Administrator for Air & Water Programs
               Allen Cywin, P.E.
     Director, Effluent Guidelines Division

          Dr. Charles R. Nichols, P.E.
                Project Officer
                 December ,  1973

          Effluent Guidelines  Division
        Office of Air and Water Programs
      U.S. Environmental Protection Agency
            Washington,  D.C.   20460
                           6Q6QJ*

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PROTECTION

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  EXECUTIVE OVERVIEW

  Development   Document   for   Proposed  Best  Technology    Available   for
  Minimizing    Adverse    Environmental  Impact  of   Cooling  Water  Intake
  Structures.

  Introduction

  Water withdrawal  for cooling by  industrial point  sources  now  amounts   to
  approximately 70  trillion  gallons per year.   Steam  electric  powerplants
  withdraw approximately  80%  of  this,  or   60  trillion gallons  per year
  which  is  roughly 15% of  the total flow of waters in  U.S.  rivers  and
  streams.  The intake of cooling  water by broad categories of  industry is
  given in Table A.  The  relative  potential  significance of average  intake
  cooling water volumes for establishments within the  broad categories   is
  shown  in  the  table.   However,  the maximum cooling water  volumes  for
  individual establishments will be dependent on factors such as  products,
  processes employed, size of  plant, degree  of recirculation  employed   in
  the cooling water  system, etc.
                                 TABLE A
                     Intake of Cooling Water by Broad
                    Categories of Industry  (Year 1967)
 Category
 Intake Volume
Billion gal/yr
 Steam Electric Powerplants   40,000
 Petroleum Refineries
 Primary Metals Mfg.
\Chemical Plants
 Pulp and Paper Mills
 Rubber Mfg.
 Wood Products Mfg.
 Pood Products Mfg.
'Stone, Clay, & Glass Mfg.
 Textile Mills
 Leather Mfg.
       1,230
       3,630
       3,530
         650
          96
          52
         430
         140
          24
           1
NO. Of
Estab

1,000
  260
  840
1,130
  620
  300
  190
2,350
  590
  680
   90
       Avg.  Intake
Billion gal/vr/estab
         40
          4
          4
          0,
          0,
          0,
          0.
          1.1
          0.04
          0.01
 Adverse  environmental  impacts  that  could  occur  from  cooling water
 intakes relate to the net  damage or destruction of benthos,  plankton and
 nectonic organisms by external interaction with the  industrial  cooling
 system.    Important  aspects  of  the  intake  which  relate  to adverse
 environmental  impact are the intake volume,  the  number  and  types  of
 organisms  which  interact  externally with the intake or which interact
 internally with the industrial cooling  system,  the  configuration  and
 operational characteristics of the intake and plant cooling system, the
 thermal  characteristics  of the cooling system, and the  chemicals  added
 to the  cooling system for  biological control.
                                  111

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The   above  impacts  are  highly  site-specific.    Therefore,   adequate
biological data would be needed in each case to determine  the   specific
need  and control strategy related to minimizing environmental  impact of
intake structures.

Applicable Technology

The range of technologies corresponding to the control of the number and
types  of  organisms  which  interact  externally  with  the  intake  is
comprised  of  two  factors  -  the choice of the location of the intake
relative to the location of the organisms; and the full array of process
modifications including the use of recirculating cooling  water  systems
employing  offstream  means  to  transfer  process  heat directly to the
atmosphere, to minimize or in some cases eliminate the  use  of  cooling
water.  The technology for controlling the number and types of organisms
which  interact  internally  with the cooling system is comprised of one
factor in addition to location and flew volume controls as  cited  above
for intake interactions, i.e., the degree to which the conriguraticn and
operation of the intake means prevents the entry of these organisms into
the  cooling  system.   The technology for preventing the entry of these
organisms while minimizing damage due to external interactions with  the
organisms  is diverse, including a multiplicity of physical and behavior
barriers and including various fish bypass and removal systems.

Damage due to internal interactions with process cooling systems  relate
to the design and operation of these systems with respect to mechanical,
thermal,  and  chemical characteristics.  For example, the presence of a
cooling tower in a nonrecirculating  ccoling  system  could  affect  the
amount  of  organism damage due to the pumping, temperature changes, and
possible chemical additives employed with the tower.

The extent of the known present application  of  these  technologies  to
industrial  cooling  water  intakes is extremely limited, and is largely
confined to steam  electric  powerplants.   However,  some  technologies
applicable  to  industrial point sources have been applied to irrigation
potentially and other flows.

Costs

The choice of intake location, while a potentially available  technology
to some degree for all industrial sources for controlling the number and
types  of  organisms  interaction  with the intake, could be more costly
incrementally in  the  case  of  relocating  an  existing  intake,  than
applying a recirculating cooling system to minimize or eliminate cooling
water flow.  In general, the incremental costs associated with caoice of
intake  location  or  application  of  recirculating  cooling systems to
control the number and types of organisms interacting  with  the  intake
would  be  less  for  a  new  source than for a similar existing source.
However,  little  is  known  concerning  incremental  costs   since   no
                               IV

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industrial  point  source,  new or existing, is known to have added this
technology (location).

Some information is available concerning the performance  and  costs  of
various  intake  devices in specific applications both at steam electric
powerplants and elsewhere.  However, the reliability of  predictions  of
performance  at  one site based on performance at anotaer site is low in
many cases.

No modification of a process cooling system is known to have  been  made
by  any  industrial  point  source  to  minimize  damage due to internal
interactions.   However, modifications,  such  as  the  incorporation  of
helper cooling towers to meet environmentally imposed temperature limits
on  discharges  from  nonrecirculating  cooling water systems, have been
made to steam electric powerplants which could have  possibly  increased
damage  to  organisms  interacting  internally  with  the  cooling water
system.

Nonwater Quality Impacts

Energy  requirements  of  available  control   technologies   would   be
significant  in  individual  cases,  only in relation co the extent that
certain types of recirculating cooling water systems would  be  employed
to minimize or eliminate the use of cooling water.

Energy  requirements  and  nonwater  quality environmental impact of all
other available technologies are not known to be significant.

Best Technoloqy_Ayailablg

Owing to the highly site specific cost versus  benefits  characteristics
of  available  technology for minimizing environmental impact of cooling
water  intake  structures  no  technology  can  be  presently  generally
identified   as   the  best  technology  available,  even  within  broad
categories of possible application.  Within this context, a prerequisite
to the identification of best technology available for any specific site
could be, in some cases, a biological study  and  associated  report  to
characterize  the  type,  extent,  distribution, and significant overall
environmental relation  of  all  aquatic  organisms  in  the  sphere  of
influence  of  the  intake, and an evaluation of corresponding available
technologies,  in accordance with generalized guidelines to identify  the
site   specific   best   technology  available  for  minimizing  adverse
environmental impact of cooling water intake structure.  Studies of  the
type  outlined  above  could  have  a  severe economic impact on certain
relatively small  establishments  with  relatively  high  cooling  water
intake volumes.  From a nationwide perspective the costs versus benefits
of  full  studies corresponding to all establishments with cooling water
intake has not been shown to substantiate the requirements that all such
establishments be required to submit reports of such studies.   Further,
in  the case that incrementally costly intake structure technology would

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be shown to be required, expenditures beyond the cost  of  recirculating
cooling  water  systems would generally not be prudent since that option
would remain to significantly reduce the intake volume of cooling water.

Requirements regarding the application of best technology available  for
intake   structures   could   be  very  costly  in  the  case  of  small
establishments, point sources facing a later requirement  under  section
304(b)  effluent  guidelines  to  meet  thermal limitations reflecting a
recirculating  cooling  water  system,  or  where  the  best  technology
available for intakes would require relocation of the intake.

Certain general guidelines have been developed for site characterization
and   the  description  of  location,  design,  construction,  capacity,
operation and maintenance features of cooling water intake structures to
reflect the  best  technology  available  for  minimizing  environmental
impact.   These guidelines and supporting data are presented in the body
of the report.
                                VI

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                                CONTENTS



Section                                                   Paqe
                                                             • i-


    I     Background                                       ..



   II     Location                                         _



  III     Design



   IV     Construction                                    ,?t-



    V     Operation and Maintenance



   VI     Cost Data



  VII     Conclusions  and Recommended Technology

          to  be Considered in Each Case



VIII     Acknowledgements



   IX     References



    X     Glossary
                              Vll

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                                FIGURES

Number                      Title


1-1        Schematic Diagrams Typical Intake Structure           3

II-1       Intake Location With Respect to Shoreline            11

II-2       Location of Intake and Outfall - Plant No. 5502      14

II-3       Location of Intake and Outfall - Plant No. 0608      15

II-U       Intakes Drawing From Different Water Levels          17

III-1      Loss of Head Through Traveling Water Screens         21

III-2      Intake Velocity vs Fish Count                        24

III-3      Mean Cruising Speed for Under Yearlings  and          24
           Yearling Coho Salmon for Four Levels of
           Acclimation

III-I4      Effective Screen  Area                                26

III-5      Undesirable Intake Well Velocity Profiles            27

III-6      Screen Mesh Size  selection                           30

III-7      Typical Electric  Fish  Fence                          32

III-8      Air  Bubble Screen to Divert  Fish from  Water  Intake  35

III-9      Channel to Test  Effectiveness  of Air  Bubble  Screen  35
           at North Carolina Fish Hatchery

111-10     Bubble Screen  Installation  at  Plant No.  3608 To     38
           Repel Fish from  Water  Intake

111-11     Louver Diverter  - Schematic                          41

111-12     Delta Fish Facility  Primary Channel System          42

111-13     Test Flume  at  Plant  No.  0618                        44

III-1U      Intake  Structure -  Plant No. 0629  To Divert Fish by 45
           Louver  Screens and  Return Them Downstream

 111-15      Fish Elevator  for Fish Bypass - Plant No. 0629      47

 111-16      operation of the Velocity Cap                       49
                                  Vlll

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 Number                      Title
111-17     Conventional Vertical Traveling Screen                 53

III-18     Conventional Vertical Traveling Screen                 54

111-19     Traveling Water Screen                                 56

111-20     Inclined Plane Screen with Fish Protection             58

111-21     Fixed  (Stationary)  Screen Detail                       60

111-22     Fixed  (Stationary)  Screens                             61

III-22a    Perforated Pipe Screen                                 63

111-23     Double Entry, Single Exit Vertical Traveling Screen    64

111-24     Double Entry, Single Exit Vertical Traveling Screen    65

111-25     Double Entry, Single Exit Vertical Traveling           66
           Screen, Open Water  Setting

111-26     Single Entrance, Double Exit Vertical Traveling Screen 69

111-27     Single Entry, Double Exit Vertical Traveling Screen    70

111-28     Horizontal Traveling Screen                            71

111-29     Mark VII Horizontal Traveling Screen                   73

111-30     Adaptation of Horizontal Traveling Screen              75

111-31     Revolving Drum Screen-Vertical Axis                    76

111-32     Vertical Axis Revolving Drum Screen                    77

111-33     Revolving Drum Screen - Horizontal Axis                79

III-3I4     Fish Bypass Structures                                 81

111-35     Single Entry Cup Screen                                82

111-36     Double Entry Cup Screen                                83

111-37     Screen Structure With Double Entry Cup Screening       34

111-38     Double Entry Drum Screen Open Water Setting            86

111-39     Rotating Disc Screen in Operation                      87
                                 IX

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Number                       Title                                Pa
                                                                  •3 __

111-40     Fish Basket. Collection  System                         90

111-41     Modified Vertical Traveling  Screen                    92

111-42     Shoreline Pump and Screen Structure                   94

111-43     Conventional Pump and Screen Structure                95

111-44     Pump and Screen Structure with Skimmer Wall           96

111-45     Pump and Screen Structure with Offshore  Inlet         93

111-46     Profile Through Water Intake - Siphon Type            99

111-47     Approach Channel Intake                              100

111-48     Screen Location - Channel Intake                     101

111-49     Shoreline Intake Structure                           103

111-50     Flush Mounted Screens - Modified and                 104
           Conventional Screen Setting

111-51     Pump and Screen Structure                            105

111-52     Pump and Screen Structure                            106

111-53     Pier Design considerations                           108

111-54     Screen Area Velocity Distribution                    109

111-55     Factors Contributing to Poor Flow Distribution       no

111-56     Pump/Screen Relationships
111-57     Pump and Screen Structure for Low Intake             113
           Velocities

111-58     Effects of Pump Runout                               114

111-59     Pump and Screen Structure with ice Control           n6
           Feature

111-60     Infiltration Bed Intake - Plant No. 4222             118

111-61     Infiltration Bed Intake - Plant No. 5309             120

111-62     Perforated Pipe Intake                               121

111-63     Radial Well Intake                                   122

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 Number                         Title
 	                         1J-T-xe                                  Page





 III-6U      Angled Conventional  Traveling  screens                  124



 VI-1        cost  of Intake Systems                                   136



 VI-2        Design of Conventional  Intake                           140



 VI-3        Design of Conventional  Intake  Modified  by Design     141

             Recommendations
                              LIST OF TABLES





Number                         Title





  A         Intake of Cooling Water by Broad Categories of Industry       iii



III-l       Fish Maximum Swimming Speeds                                  23



III-2       Traveling Water Screen Efficiencies                           28



III-3       Electric Screen Applications - Summary of Design Data          33



 VI-1       Cost of Traveling Water Screens                              135



 VI-2       Cost of Intake Structures                                    138



 VT-3       Cost Analysis - Implementation of Design Requirements         139
                                   XI

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                               SECTION I

                               BACKGROUND
The Federal Water Pollution Control Act Amendents of  1972  state  under
"Thermal  Discharges," Section 316(b): Any standard established pursuant
to section 301 or section 306 of this Act  and  applicable  to  a  point
source  shall  require  that  the  location,  design,  construction  and
capacity of cooling water intake structures reflect the best  technology
available for minimizing adverse environmental impact.

This  statement  allows  considerable  latitude  in  its interpretation.
Rather than calling for an explicit control and treatment technology  to
be  broadly  applied  as  in  Section  301, Section 316(b)  requires that
intakes shall  incorporate  "best  technology  available"  in  terms  of
location,  design,  construction  and  capacity.   The Act also does not
indicate whether new intakes are to  be  treated  any  differently  than
existing intakes.

In  addition,  performance  and  maintenance are important factors which
should be considered in addition to those itemized in the Act.  The term
"capacity" relates to the physical size  of  an  intake,   and  has  been
considered  as an integral part of design considerations.  Consequently,
this report has been divided into the following sections  for  location,
design, construction and operation and maintenance.

Since  the  Act specifies cooling water intake structures,  this document
is addressed specifically to these types of  intakes.   It  is  evident,
however,  that  the  discussion could apply to many other types of water
intakes;  for  example,  non-cooling  water  intakes   for   industrial,
irrigation  or  domestic  water supply.  A major feature of a powerplant
intake,  as  distinguished  from  many  others,  is  the  necessity  for
continuous  operation.   Such a requirement imposes many design criteria
that may not be  necessary  for  other  types  of  intakes.   Powerplant
intakes  cannot  normally be shut down to bypass temporary fish runs, to
clean out silt or to lessen some other  seasonal  environmental  impact.
However,  shutdowns  may be feasible in some instances as with a nuclear
powerplant scheduling refueling for a predictable critical fish spawning
period.

Intake Structure Definition

From an environmental standpoint, an intake consists of all elements  of
a  water  drawing  facility  from  the point of water inlet to the water
screens.  The water screens are the last point in the circuit  at  which
aquatic  life  can  be  recovered.  Common usage also often includes the

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circulating and service water pumps, where those pumps  are  located  in
the  same  structure  as the screens.  However, these are not strictly a
functional part of the intake,  from an environmental standpoint.   Figure
1-1 shows two typical intake structures designating  those  parts  which
define the intake for the purposes of this study.

Cooling  water  intakes  for  industrial  point  sources fall into three
general categories according to the magnitude of the water flow and  the
physical size of the structures involved.

Circulating  Water  Intakes - These intakes are for once-through cooling
systems,  which  are  designed  to  continuously  withdraw  the   entire
circulating  water  flow.  The water is passed through tne condenser and
returned to the water source.  The typical water  usage  for  which  the
intake  for  powerplants must be designed is from about 0.03 to 0.1 m3/s
(500 to 1500 gpm)  per MW.

Makeup Water Intakes - These intakes provide the water to  replace  that
lost  by  evaporation,  blowdown  and drift from closed cooling systems.
The quantity of water required is commonly 3 to 5%  of  the  circulating
water  flow.   These intakes are therefore considerably smaller than the
cooling water intakes for once-through systems.

Service Intakes - These intakes provide the water required for essential
cooling systems as in the case of a nuclear powerplant.  Here, the water
quantity is small when compared to the circulating water flow, averaging
about 0.002 m3/s  (30 gpm) per MW of capacity.   The  structure  will  be
quite  massive  due  to  the  requirements for redundancy of pumping and
screening equipment  and  the  need  for  both  missile  and  earthquake
protection.   From  an  environmental  standpoint,  visual impact may be
substantial.

Often service water  systems  and  circulating  water  systems  will  be
contained  in  separate  bays at the same intake.   Most new intakes will
have this design.  Older powerplants, built in a  series  of  steps  may
have  separate intakes for different functions and may use more than one
water source.


Environmental Impact as Related to Intake Structures

The major impacts caused by cooling water intakes  are  those  affecting
the  aquatic ecosystem.  The aquatic organisms comprising this ecosystem
may be defined in broad terms as follows:

Benthos - Bottom dwellers are generally small and sessile (non-swimming)
but can include certain large motile species (able to  swim).   Location
of  major  populations  can  be  reasonably  well  defined and therefore
avoided by adoption of appropriate locational guidelines.  These species
can be important food chain members.

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             Traveling Screens
Trash, Rack
                                      Circulating Water
                                            Pumps
                                        5  Water to Plant
Inlet
Structure
                       Manual
                     Fine Screens
      Inlet Condui
Canal to Plant
and Circulating
Water Pumps
                                                    \\
          SCHEMATIC DIAGRAMS TYPICAL INTAKE STRUCTURE
     (Point of Water Inlet to the Water Screening Facility)

                        FIGURE  1-1

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Plankton - Free floating microscopic plants  and  animals  with  limited
ability  to swim.   The location of these species generally are apt to be
rather diffuse throughout the water body and therefore the  adoption  of
locational  measures would not protect these species.  However, vertical
movement of some species is controllable leading to the  aggregation  of
many  plankters into layers.  Locational measures, sucn as withdrawal of
water from hypolimnetic waters, may serve to protect vulnerable plankton
layers.  Plankton are also important food chain organisms.

Nekton - Free swimming organisms  (fish).  Of major concern in many cases
are egg and larval stages which are small and have limited mobility  and
therefore  generally considered as plankton.  Adult fish of most species
will have the swimming ability to avoid the  intake  provided  they  are
stimulated  to  do  so.   The location of spawning and nursery areas and
migration  paths  are  frequently  definable  and  therefore  should  be
reflected in locational measures.

One  of  the  first  steps  that may be taken in the proper location and
design of a  cooling  water  intake  structure  from  the  environmental
standpoint  is the designation of the organism(s)  to be protected.  This
approach has been outlined by  the  U.S.  Atomic  Energy  commission  in
reference  24.   This approach requires the determination of the species
present in the area of the intake.  A determination of their spatial and
temporal distribution is also required.  A judgment may then be made  as
to  which  of  the  identified species are critical to the ecosystem and
therefore  would  control  the  environmental  design  of   the   intake
structure.   It  is  sufficient  to  say  at this point that the control
strategy for minimizing  environmental  impact  will  be  different  for
planktonic species than for nektonic species as disucssed below.

Impacts on Aquatic Organisms

Impingement  -  The entrapment of nektonic species against a screen mesh
by velocity forces across the screen.  In general, impingement  will  be
lethal  for  most species due to  starvation and exhaustion in the screen
well, descaling by screen wash sprays and by asphyxiation due to removal
from water for prolonged periods of time.

Entrainment - The passage of relatively small  benthic,  planktonic  and
the  smaller  nektonic  forms   (egg  and  larval)  through the condenser
cooling system.  Mortality of these organisms is quite variable and is a
subject of considerable on-going  research.  Damage can occur from one or
more of the following causes:

- physical impact in the pump and condenser tubing

- pressure changes across the condensers

- thermal shock in the condenser  and discharge tunnel

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- chemical toxemia induced by  antifouling agents such as chlorine

Entrainment is not an impact of  the  intake  structure  but  rather  an
effect caused by the subsequent condenser cooling water system.


Control_Strategy_fQ£_Ljmiting  Impacts on Aquatic Organisms

As  indicated  above,  the  control stategy for minimizing environmental
impacts at intake  structures  will  vary  with  the  type  of  organism
considered.   Impingement  effects  can  be  significantly influenced by
both the location and design of intake structures.  This is because  the
spacial  and temporal distribution cf nektonic species can be reasonably
well defined by biologic examination, and  sensitive  areas  avoided  by
proper  location of the intake structure.  In addition, the size of some
adult nektonic species is sufficient to allow their impingement on  fine
mesh screens.  Entrainment effects on the other hand are relatively less
controllable  by  intake  structures.   This  is because the size of the
species are small and they generally  lack  significant  mobility.   The
spacial  and temporal distribution of these species is more difficult to
define, which will limit the   effectiveness  of  locational  guidelines.
Design  strategies  will also  be generally ineffective for these species
since their small size and lack of swimming ability  will  prevent  them
from being effectively screened on a fine mesh screen.

There  are  more  effective  ways  to  control entrainment effects where
benthic and planktonic  organisms  are  identified  as  critical  design
organisms.   One  approach would be to limit the volume of cooling water
withdrawn from a source to a small percentage of  the  makeup  water  to
that  source.   This  would  be  a  limitation placed on intake capacity
rather than other an intake specification.  For new  plants  this  would
mean that the large capacity intakes would be located further downstream
and smaller intakes located upstream.  Peterson 16 has made estimates of
the  thermal  capacity  of  some of the Nation's larger waterways.  This
work could be expanded upon to establish  relationships  between  intake
volume  and mean flow.   Where existing stations exceeded the recommended
volume,  steps  would be taken to reduce the intake volume.  Implicit in
this approach is that the impact of entrainment effects on  a  waterbody
is  related  to  the volume of intake flow, i.e., the lower the flow the
lower will be  the  damage  to  planktonic  and  benthic  species.   The
limiting  intake  volume  is  that  at  which  the  waterbody is able to
compensate for the damage to entrained organisms.

Another approach would be to design the cooling water system to minimize
the effect on entrained organisms.   This approach involves limiting  the
temperature,   pressure,   chemicals  added,  and  time of exposure of the
aquatic species to levels that will insure satisfactory survival of  the
design  organisms.    A  considerable amount of research has been done on
the subject of survival of entrained  organisms  after  passage  through
condenser cooling water systems.   The results of these studies are often

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conflicting.  A suggested guideline in this area has been offered by the
National  Academy of Engineering,3* which recommended that the condenser
system be designed according to the following formula:


    t ( T)   > 2000

    t = exposure time in seconds

    T = temperature rise across the condenser (°C)

This formula implies that higher temperature rises could be tolerated by
most species if the exposure  time  were  kept  to  a  minimum.   It  is
believed that the experimental data upon which this formula is based was
limited  and  therefore  caution is suggested in the application of this
formula.

It is noted that this approach is  directed  at  the  condenser  cooling
system and is not applicable for intake structures.

Other Environmental Impacts Related to the Intake Structure

Aesthetic  Impact  - Where the intake structure and balance of plant are
separated by great distances the intake structure may have  an  imposing
physical  presence.  This will be significant in wilderness areas and in
natural and historical preserves.  Where plant and  intake  are  located
close  together  architectural  treatment  can  be  applied to create an
attractive appearance.

Noise Impact - The sound level of the large  circulating  pumps  can  be
quite  high.   Current practice in milder climates is to construct these
installations without  enclosures.   Enclosed  intakes  would  not  have
significant sound levels.

Acquisition of Biological Data

Probably  the  most  widely ignored aspect of data collection for intake
structure design is the  biological data on the aquatic  species  to  be
protected.    Most  of  the  data  collected  for intake structure design
concerns the hydrological information  relative  to  the  water  source.
This  information  consists  of  data  on water currents, sedimentation,
water surface elevations and  water  quality.   In  general,  relatively
little  data  on  the  biological organisms is collected.  The design of
intakes should be based on protection of the critical aquatic  organisms
as  well  as  the  traditional  design considerations of adequate flows,
temperatures and debris removal.  In addition, it has  been  noted  that
the  design  criteria for the protection of the aquatic environment will
be significantly different for different species in  the  water  source.
It is therefore necessary that in each case sufficient data must be made
available  on  the  biological community to be protected.  The data that

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must be provided in some cases, depending on the severity of the problem
and especialy for new steam electric pcwerplants withdrawing water  from
sensitive water bodies, should consist of, as a minimum, the following:

   The  identification of the major aquatic species in the water source.
This should include estimates of population densities for  each  species
identified,   preferably   over   several  generations  to  account  for
variations which may occur.

- The temporal and spacial distribution of the identified  species  with
particular  emphasis  on  the  location  of  spawning grounds, migratory
passageway, nursery area, shellfish beds, etc.

- Data on source water temperatures for the full year.

- Documentation of fish swimming capabilities for the species identified
over the temperature ranges anticipated and under test  conditions  that
simulate as closely as possible the conditions at the intake.

   Location  of  the  intake  with  respect  to the seasonal and diurnal
spatial distribution of the identified aquatic species.

The criteria for the biological survey   for  the  development,  of  this
data is not presented here.  There are several excellent publications on
the  techniques to be used in the conducting of biological surveys.  The
EPA has published guidelines for the conduct of  bioligical  surveys.  9
The techniques will differ both with the type of organism and the source
of water.

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                               SECTION II

                                LOCATION
Introduction

Both the location and design of cooling water intakes can jtiave an effect
on  the  environment.   This  section is concerned primarily with intake
location, although it will become evident that location and  design  are
closely associated in many respects.

"Intake"  as  previously defined, means the entire intake facility which
may consist of one or more elements including an  inlet  structure   (the
point  of  water  entrance)  closed conduits and open channels to a pump
structure or a combined screen and pump structure.  "Location" refers to
both the horizontal and vertical placement of the intake with respect to
the local above-water and under-water topography.  This section attempts
to answer such questions as:  where is the intake  to  be  located  with
respect to the shoreline, navigation channels, discharge structures, and
fish spawning areas?  Also, from what depths is the water to be drawn?

The  discussion  is  concerned  with  three  locational  aspects  of the
intake's relation to the environment:

    The  operation  of  the  intake  insofar  as  its  location  affects
    operational  characteristics.   Operation will usually result in the
    major  environmental  influence  to  be  expected  from  any  intake
    facility.

    Construction activities such as dredging,  excavation  and  backfill
    for  channels, inlet conduits, inlet structures, and pump and screen
    structures.  The environmental influence may  be  considerable,  but
    will normally be temporary if suitably controlled.

. •  Aesthetics,  the  appearance  of  the  intake   facility   and   its
    relationship  to the surroundings.  Both the design and the location
    of one or more elements of the intake facility may  be  dictated  in
    part by aesthetic considerations.

The  most  important  locational factor influencing the intake design is
the nature of the water source from which the supply is being taken.

Other locational factors which  must  be  considered  are  the  relative
location   of  the  intake  structure  with  respect  to  the  discharge
structure, the vertical location of the  intake,  the  location  of  the
intake  with  respect  to  the balance of the plant and the avoidance of
areas of important biological activity.  In all water bodies, the intake

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may be located off-shore, flush with the shoreline  or  inland  with  an
approach  channel as shown in Figure II-l.  The reasons for selection of
a particular orientation with respect  to  the  shoreline  are  both  to
provide  the required volume of the coldest available water and to avoid
drafting from biologically sensitive areas.


Water Sources


Fresh Water Rivers

Rivers normally are characterized by unidirectional  flow,  which  eases
the  intake  design  problem.   Most large rivers will generally possess
sufficient resistance to recirculation due to the velocity  gradient  to
permit  the  siting  of  both  intake  and  discharge  at the shoreline.
Recirculation might present a problem at extremely low flows.  The  base
of  the river intake is generally set at the lowest river bed elevation,
however, it should  be  set  above  significant  silt  accumulations  to
prevent  silt  deposition in the intake.  Different locations in streams
have different susceptibilities to silting.  The inner  sides  of  river
bends  are more susceptible to silting than the outer sides.  The top of
the intake is usually set for high flow and flood conditions.  The  pump
operating  deck  is  usually  placed  several feet above the flood crest
level.  Frequently, large water levels  and  flow  variations  can  make
river intake structures correspondingly high.

Ice  flows  and  debris  loading  are  also  significant  for many river
locations as are the maintenance of navigation  passages.   Rivers  will
usually  possess  minimum  temperature  stratification  when compared to
lakes because of greater vertical and horizontal mixing.  Finally, it is
necessary to protect the aquatic life from entrapment in the intake.  In
doing this, it  is  best  to  locate  the  diversion  structure  at  the
shoreline  and  employ  the sweeping currents of the river to carry fish
downstream.  However, such a structure  could  trap  upstream  migrants,
leading them to the intake structure.


Fresh Water Lakes and Reservoirs

The  most  significant  difference  between lakes and rivers is the fact
that the former are often stratified with respect to  temperature.   The
thermal  stratification  of  lakes  is a rather complex phenomenon.  The
heat balance of a lake depends on ambient air temperature, wind  speeds,
the  topography  of  the lake bottom and  flows into and out of the lake.
It is clear that a large withdrawal or discharge of  cooling  water  can
significantly  affect thermal stratification.  The zone of cold water at
the bottom of the lake is called the  hypolimnion.   The  water  in  the
hypolimnion  is  relatively  low  in  dissolved oxygen and often high in
nutrients  (nitrates, phosphates).
                                  10

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                A,
                < '\
      WATER   V.

      SOURCE

             r
     WATER


     SOURCE
w
 ££:
             TO POWER PLANT
                 INLET FLL/SM  WITH  SHORELINE
              I    I
                    |.L
             TO POWER PLANT
                  OFFSHORE  INLET
      WATER


      SOURCE
CANAL
TO

 PLANT
        OPFN CANAL TO INLET
            INTAKE LOCATION WITH RESPECT TO SHORELINE


                       FIGURE H-l


                           11

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Lying above the hypolimnion of a stratified lake is a zone of distinctly
warmer water,  the epilimnion.   The significant features of this zone are
that it is the area from which evaporation takes place; it is the region
into and out of which the natural stream courses  flow;  it  washes  the
shoreline or littoral zone which is a region of highly abundant life and
it supports considerable populations of life throughout its extent.  The
water  in  this  zone  is  usually high in dissolved oxygen.   Artificial
reservoirs may have poorly defined littoral zones  because  of  drawdown
procedures.   While the littoral zone of a reservoir would be attractive
because it does not support as much life, it is of  little  use  to  the
intake designer who will find a shoreline intake too often high and dry.

Within  the  epilimnion is the uppermost zone which is called the photic
zone.  The productivity of this zone is a  function  of  the  degree  of
penetration  of  sunlight  and  the presence of necessary nutrients.  As
little water as possible should be taken from  the  epilimnion  and  the
absolute  minimum from the photic zone.  Off-shore intakes with multiple
entrance ports appear to have great application in stratified lakes.

Lakes generally do not have the pronounced flushing currents  that  many
rivers  have.    Therefore, the possibility of recirculation becomes more
significant.  In addition, there is no assistance by current flushing to
wash debris and fish past the intake.

Wind forces  provide  most  of  the  water  level  variation,  and  wave
protection is an important design consideration in intake structures for
lakes.   Commercial navigation is generally not as important a factor as
in rivers, since shoreline  and  dams  prevent  access  to  most  lakes.
However,  recreational  use  is  more  prevalent  on   lakes than in many
rivers.  The Great Lakes  constitute  an  important  exception  to  this
generalization regarding navigation.

Estuaries


A number of factors combine to make intake design and  location selection
for estuaries the most difficult of all water source types.  Flow  is two
directional  which  complicates  the  design  of many  screening systems.
Similar  to  lakes,  most  estuaries  exhibit   stratification,  although
stratification  in  estuaries  is  generally  less stable than in  lakes.
Water  density  depends  on  both  water   temperature   and   salinity.
Volumetric  fluctuations   are  greater due to the periodic influx  of sea
water.  The salt content varies with tidal cycles.   Estuaries  are   often
stratified  with  respect  to  salt content, with fresh water  tending to
ride above the salt.   In areas where cooling water discharge  effects are
present, density stratification in potential  intake   areas   is  further
complicated  by  the   differing   buoyancies of  warm  and cool   water, and
fresh  and  salt water.
                                 12

-------
 Estuaries are  frequently major  spawning  areas  for both   ocean   fish   and
 shellfish,  with  wide  seasonal  variations   of biologic  activity.   The
 presence of current  reversals  can   also  create   severe   recirculation
 problems.   Because  of the high  salt content  and tidal  variations which
 create periods of high  and  low  water,   corrosion becomes  much  more
 significant in intakes designed for estuaries.


 Oceans

 The  most  important consideration in the  design of ocean  intakes is  the
 storm wave protection system.  Viave damping upstream of  the  screens   is
 required.   There  may  also  be  heavy  sediment load in  the surf area.
 Other  factors  to  be  considered  are  littoral   drift  and   shoreline
 instability.   The  littoral  zone  is   highly  productive  biologically,
 although generally not as productive  as  are estuaries.

 Thermal stratification exists but is  not as  stable  as  that   in  lakes
 because  of the higher degree vertical turbulence in oceans.  Navigation
 passageways must also be considered.


 Intake_Lgcation with Respect, to Plant Discharqg

 From the point of view of plant cooling water requirements  tne  use  of
 coolest   available   water  is  desirable.   Accordingly,  considerable
 attention  has  normally  been  given to   avoiding   the   inadvertent
 recirculation of warm water discharge back into the intake.  From a fish
 attraction   standpoint,   the   avoidance   of  recirculation  is  also
 advantageous.  Long experience has shown that many  species  of fish  tend
 to  congregate  in warm water areas,  especially in the cooler seasons of
 the year.  In at least one  major  nuclear  plant,  a  small  amount  of
 recirculation  attracted  fish  to  the  intake area in winter.  The fish
 thus attracted were also lethargic due to the low winter temperatures of
 the water and they tended to be carried into the screens.

 The technical aspect of the avoidance  of  recirculation  is  a  subject
 beyond  the scope of this study.  Note, however, that  the subject would
 involve an analysis of the existing water currents,   the  stratification
of the warm water and the dilution and dispersion characteristics of the
discharge structure.

There  are  a number of ways in which recirculation can be avoided.   Two
of these are shown in Figures  II-2 and  II-3.    Figure  II-2  shows  the
location  of  two intakes and  discharges at plant no.  5502.  The methods
used at this plant to prevent  recirculation is to locate  the  intake  a
considerable   distance  off-shore  and  locate  the  discharge  at  the
shoreline.   Figure II-3 shows  the location of  the intake and outfall for
plant no.  0608.  This plant avoids recirculation  by  withdrawing  water
from  one body of water and discharging to another body of water.  Other
                                13

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LOCATION OF INTAKE AND  OUTFALL - PLANT NO. 5502

                 FIGURE 'LI~2
                       14

-------
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                            MOSS LANDING HARBOR
LOCATION OF  INTAKE AND OUTFALL - PLANT NO.  0608
                 FIGURE H-3
                    15

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ways of avoiding recirculaticn are to separate intake and outfall  by  a
sufficient  distance, the construction of a physical barrier between the
intake and outfall, and the excavation of a channel for  the  intake  or
outfall  or  both.   Prevention  of recirculation also requires adequate
vertical separation of intake and discharge.  This  is  importanr  in  a
stratified  water  body such as a lake.  Vertical separations of between
20 to 60 feet have been used at some locations.

From the standpoint of the effect of recirculation on  fish  attraction,
it  should  be  noted  that proper location of the inlet point both with
regard to site location and water depth, is an important design  element
to be considered.


Intake Lo_cation_with__Resggct_to^the_Shprgline

As  mentioned  above  and  shown  in  Figure II-l, there are three basic
orientations of intakes with respect to the shoreline.   Tne  difference
between them is the relative position of the water inlet with respect to
the  shoreline.  The intake at the top of the figure has the inlet flush
with the shoreline.  This intake may also be called a  shoreline  intake
or  a bankside intake.  The middle intake has the inlet located offshore
with a conduit leading to the shore.  The offshore inlet may be  only  a
pipe  opening  as  shown,  or may include water screening facilities and
pumps.  The third type of intake uses an open channel  inlet   (generally
excavated)  leading  to an inland water screening facility.  This latter
type of intake may also be referred to as an onshore intake.

Each of these different intake orientations may be used for any type  of
water  source  (river, lake, estuary, or ocean).  The flush inlet and the
offshore inlet offer alternate means  for  withdrawing  water  in  areas
where  aquatic  population  may  be  minimal.   The  third  scheme  (open
channel) may have  desirable attributes from an aesthetic point of  view,
but often creates  a  problem due  to fish which  collect in open channels.
This aspect will  be  discussed in the design section of this report.


Intake Location with Respect^to  Water  Depth

From   the  biological  standpoint,  the  depth   at which  water  is taken  can
be  a major  factor regarding   damage   to   aquatic  organisms.    In   some
locations,  it   may  be desirable  to draw  surface water only  as  shown  in
Part A of Figure  II-U.  At  other locations, it may   be  better   to   draw
deep   water  as   shown  in   Parts  B  and  C  of  the  figure.  A  complicating
factor is that  the desirable  water supply  depth may  vary  seasonally   or
even diurnally,  making multilevel  intakes  environmentally attractive.   A
typical   multilevel  intake is shown in  Part  D of  the  Figure.. For  water
sources where  the biologic  community is  extremely   sensitive   to  intake
currents,   a deep intake  of the  infiltration  type  might be  best  as  shown
in  Part  E of the figure.
                                  16

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SURFACE  INTAKE
      (A)
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                              DEEP  INTAKE
                                     (3)
         DEEP INTAKE
               K)
                               
-------
Aguatig Environmental Considerations in Intake Location

The location of the intake should also  reflect  the  knowledge  of  the
various  members  of  the  aquatic  community.   The  location should be
selected to minimize the impact of the intake on the identified species.
In general, the intake location should include the following:

    avoidance of  important  spawning  areas,  fish  immigration  paths,
    shellfish  beds  or  any  location  where  field investigations have
    revealed a particular concentration of aquatic life.

    selection of a depth of water where aquatic life is  minimum.   This
    depth may change seasonally or diurnally.

    selection of a location with respect to the river or  tidal  current
    where  a strong current can assist in carrying aquatic life past the
    inlet area or past the,face of screens (if the flush mounted type of
    setting is used for example).

    selection of a location suited to the proper  technical  functioning
    of  the  particular  screening  system to be used.  For example, the
    still experimental louver and horizontal screen  installations  have
    limiting  requirements relative to water level variations and intake
    approach channel configurations which will influence their locations
    with respect to the source of water.

The application of the  above  presupposes  that  sufficient  biological
investigation  has  been  conducted  to  establish  sensitive  areas and
important species.  The previous section of the report outlined the type
of data required in the procedure for biological data gathering.    These
data  are  essential  for  proper  intake  location.    Furthermore, when
returning bypassed fish and other organisms,  they should be delivered to
a hospitable situation.


Intake_Locatign with Respect to the Balance of the Plant


some organisms may undergo damage in the passage from the intake to  the
plant  and  on  the  return  between  the  condenser   and  the discharge
structure.   The extent of the damage is proportional  to the  temperature
and  pressure  changes  and the time of travel between the shore and the
plant.  Since the time of travel is related to the distance between  the
intake  and  plant,   it  would  be desirable, in cases where incremental
damage due to this effect would be significant,  to locate the intake  as
close to the plant as possible.  This consideration applies even more to
the location of the outfall with respect to the  plant.   Relocation of an
existing  intake  with respect to the balance of the  plant could be very
costly in many cases.
                                   18

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                               SECTION  III

                                 DESIGN
Introduction

This section  of  the  report  is  organized  to  describe  the  various
components which comprise an intake structure.  The components described
include  screening  devices,  trash  racks  and fish handling and bypass
equipment.  This organization is utilized to provide an understanding of
the function and configuration of these components.  Following this, the
description of components will be assembled into  complete  descriptions
of  intake  designs,  with  recommendations  developed  for each type of
design.  The section is presented in five parts as follows:

       Screening Systems Design Considerations

       Behavorial Screening Systems

       Physical Screening Systems

       Fish Handling and Bypass Facilities

       Intake Structure Designs
Screening Systems Design Considerations

By far the most important design consideration for screening systems  at
intake   structures   is  the  velocity  through  the  screens.   Intake
velocities are usually measured in two ways as follows:

    Approach  Velocity  -  Velocity  in  the  screen  channel   measured
    immediately upstream of the screen face.

    Net  Screen  Velocity  -  Velocity  through the screen itself.  This
    velocity is always higher than the approach velocity because the net
    open area is reduced by the screen mesh,  screen  support  structure
    and debris clogging.

Velocity  considerations  should be based on the approach velocity since
the net screen velocity is constantly changing with  debris  loading  in
the  waterway.   Another important design consideration is the selection
of the screen mesh size.  This should be based on  both  fish  size  and
debris loading considerations.
                                 19

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Other  environmental  factors to be considered in designing intake water
screens can also  affect  the  configuration  of  the  intake  structure
itself.  These factors include proper location of screens to avoid zones
of entrapment, and good hydraulic design to insure uniform flow over the
entire  screen face.  This latter element is influenced by the design of
the hydraulic passages both upstream and downstream of tne screen.   The
downstream design also includes the location of pumps.

Approach Velocities

Most  existing  water  screens  at  intake structures nave been designed
solely on debris removal considerations.  The design criteria is usually
that  a relatively low head loss be maintained across the screen at  the
lowest  water  level anticipated.  Typical velocities through the screen
mesh fall in the range of 0.61 to 0.762 meters per second  (2.0  to  3.0
feet  per second) which would correlate to screen approach velocities in
the range of about 0.24 to 0.335 mps.   (0.8 to 1.1 fps)  or higher.

Hydraulic head loss  is  an  important  design  consideration  since  it
controls  the  pressure loading on all moving parts of the screen.  Thus
lowering the head loss across the screen lowers the  operating  cost  of
the screen and increases screen life.  Head loss increases as the square
of  the  approach  velocity, and becomes even greater as debris clogging
causes increased turbulance across the screen and reduces the net screen
area.  The effect of these factors on head loss is shown in figure  III-
1.   This  plot is based on 0.95 cm  (3/8") galvanized wire mesh.  Screen
velocity which is related to screen opening is also important because of
its impact on impinged organisms.  Physical damage to impinged organisms
will increase in proportion to the velocity through the screens.

Many intermittently  operated  traveling  screens  are  designed  to  be
actuated  under  a  maximum  lead  loss  of  1.52  meters  (5 ft).  Some
traveling screens operate continuously at a lower head  loss,  generally
0.3  to 6.61 meters  (1.0 to 2.0 ft).  Some traveling screens are rotated
once every 4 to 8 hours for 5 to 10 minutes for low head losses, rotated
more often for incrementally higher head losses, and run continuously at
high speed for the highest head losses.  Many powerplant intakes include
a pump trip-out to shut off the circulating  water  pumps  automatically
when  the  head  loss  exceeds 1.52 meters  (5 ft) or when the downstream
water level drops to some predetermined level.  In the absence of such a
trip-out provision, head differential across  the  screen  will  rapidly
increase  to  the  point  of  screen collapse and possibly damage to the
pumps.

Another important design feature of traveling water screens is the  rate
of  screen  travel  when  operating.   Screens that are not intended for
continuous operation are designed for a single operating speed  of  3.05
meters  per  minute  (10 fpm), although speeds as low as 0.61 meters per
minute  (2 fpm) and as high as 6.1 meters per minute  (20 fpm)   have  been
used  at  particular locations.  For continuous screen operation  (rarely
                                  20

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    0.304
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              (FEET/SEC.)
               2         3
  0.30A      0.606      0.912.       1.22
DESIGN VELOCITY IN  METERS/SEC
                LOSS OF HEAD THROUGH TRAVELING

             WATER SCREENS Q.95 cm(3/8") OPENING



                        FIGURE III-l


                            21

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used at powerplant intakes)  or for use under  varying  flow  conditions,
two speed screens are used,  0.76 and 3.05 mps (2.5 and 10 fps)  being the
usual  speeds.   Screens  are  generally operated once per shift and are
rotated automatically in response to water level differential across the
screen face.  The importance of considering  operational  frequency  and
screen  speed  characteristics in minimizing impingement effects will be
covered in the subsequent section on operation and mainrenance of intake
structures.

Much of the reported research would  indicate  that  considerably  lower
approach  velocities  than  the 0.24 to 0.335 mps (0.8 to 1.1 fps)  range
shown above may be required  to protect against  impingement  of  certain
species  of  fish.   Table  III-1 provides a tabulation of fish swimming
capability of various species taken from Reference 21.  The table  shows
that  fish  swimming  ability  is  a  function of both fish size and the
ambient water  temperature.    An  inspection  of  the  lower  levels  of
swimming  capability  within each species shows that approach velocities
of considerably less than 0.305 mps (1 fps)  may be desirable.

Figure III-2 shows the results of additional studies of  the  impact  of
approach  velocities  on fish impingement.  These studies were conducted
at a major nuclear plant in  the Northeast and reported in .Reference 8 G.
The involved species were the white perch and striped bass.  The  figure
shows  a  marked  increase  in  impingement  above  intake velocities of
approximately 0.24 mps  (0.8  fps).  It is important  to  note  that  this
study  was not done during the critical winter months when fish swimming
ability would be at its lowest.

Figure III-3 shows the results of another study which was  reported   in
Reference  24.   This figure shows the swimming ability of young salmon.
The effects of  both  size  and  temperature  on  swimming  ability  are
significant.   Note, however, that the mean cruising speed for all sizes
is  a  relatively  low  0.15  mps  (0.5  fps)   for  the  colder   winter
temperatures.    Oxygen   level,  as  well  as  temperature,  may  be  a
determining factor in  fish-swimming  ability.   The  selection  of  the
design  approach  velocity  should  conservatively reflect tiie degree to
which the conditions of the  laboratory fish-swimming tests correspond to
the conditions of the intake considering that the  natural  behavior  of
the  fish  and  their  escape  response  are  based upon a complexity of
factors.   Furthermore,  it   should  be  recognized  that  the  approach
velocity  would influence the ability of fish to avoid the intake screen
if there is not already a horizontal  current  to  move  them  from  the
intake.   A  further  significant  parameter could be the current at the
screen itself which would determine the ease of escape of  a  fish  once
impinged and also the extent of damage to the fish while impinged.
                                22

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                              TABLE  III-l
FISH MAXIMUM SWIMMING SPEEDS
NJ
U)
Fish
White Perch






Striped Bass


Stripped Bass

cm
7.9 -
6.1 -
3.0 -
3.3 -
5.1 -
4.1 -
5.1 -
3.0 -
3.0 -
5.1 -
1.9 -
0,25-
Size
8.4
7.1
4.3
4.7
6.8
5.1
6.8
4.8
4.8
6.4
3.8
7.6
7.6 -14.0
King Salmon

3.0 -
3.0 -
3.8
4.8
Range
inch
3.1 -
2.4 -
1.2 -
1.3 -
2.0 -
1.6 -
2.0 -
1.2 -
1.2 -
2.0 -
Q.75-
0.1 -
3.0 -
1.2 -
1.2 -
3.3
2.8
1.7
1.8
2.7
2.0
2.7
1.9
1.9
2.5
1.5
3.0
5.5
1.5
1.9
Water
C
5
10
24
27
27
32
32
24
27
27
_
-
-
_
-
Temp.
F
41
50
75
80
80
90
90
75
80
80
_
-
-
_
-
Maximum Speed
all - best all - best
mps fps
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
.16 -
.19 -
.12 -
.15 -
.22 -
.22 -
.28 -
.18 -
.18 -
.33 -
.28 -
.55 -
.49 -
.28 -
.15 -
0.25
0.23
0.30
0.30
0.40
0.40
0.43
0.33
0.40
0.43
0.43
0.88
0.88
0.52
0.46
0.52
0.63
0.4
0.5
0.7
0.7
0.9
0.6
0.6
1.1
0.9
1.8
1.6
0.9
0.5
-0.81
- 0.77
- 1.0
- 1.0
- 1.3
- 1.1
- 1.4
- 1.1
- 1.3
- 1.4
- 1.4
- 2.9
- 2.9
- 1.7
- 1.5

-------
  80
                                  (FEET/SEC.)
                                  0.6        0,8
                                            1.0
        1.2
1.4
  60
or
O-
  40
ID
o
f,;
U.
   20
RESULTS OF DATA OBTAINED SPRING, 1966
 CURVE RESULTING  FRCH DATA OBTAINED  FALL, 1965
    0
     0.0
   0.061      0.122      0.183      0.244     0.305     0.366

 AVE3ASE  INTAKE CURRENT  VELOCITY  IN METERS/SEC.


               INTAKE VELOCITY VS FISH COUNT

                     FIGURE III-2
                                                                          0.426
          UJ
          c/)
          •o
           30
          UJ
          Q_
                MEAN SLOPE
                           COHO UNDER YEARLINGS   CONO YEARLINGS
                                                              1.5
                                                              1.0
                                                     Lu
             0
           23456789
             MEAN  FORK LENGTH, CM.
10
                                                              0
                 MEAN CRUISING SPEED FOR UNDER YEARLINGS AND
              YEARLING COHO SALMON FOR FOUR LEVEL OF ACCLIMATION

                               FIGURE III-3

                                      24

-------
 Effective Screen Length and Uniform Velocities

 It is important to determine the effective dimension of  screen below the
 water  line to be used in calculating the approach velocity.  Not all of
 the screen length  below  the  water  line  contributes  effectively  to
 screening.   The  effective  length  of  screen  is influenced by both the
 hydraulic design of the intake and by  bottom   effects   related  to  the
 screen boot, boot plate, etc.  Another important consideration in deter-
 mining   the   effective   screen  length  is   the  effect:  of  upstream
 protrusions, particularly the  effect  of  curtain  walls  installed  to
 select  intake  waters  from the top or  bottom  layers of the water body.
 The effect of  walls  on the effective screen area  is  snown  in  Figure
 III-4.   The  illustration shows a  wall installed to limit araft to the
 lower levels of the water body.  The  wall limits the flow  through  the
 screen  area  to a relatively narrow band at the bottom  of the screen as
 indicated on the figure.  If  walls are  installed,  only  the  effective
 screen  area  should  be used to determine the  approach  velocity.  Walls
 can also be undesirable when they create  dead  spaces   where  fish  can
 accumulate and from which they may not be able  to escape.

 Another  important  design consideration is the uniformity of velocities
 across the full face  of the screen.  An  example of poor  hydraulic design
 is shown in Figure III-5.  The sketch shows large variations in  channel
 velocities  which  greatly  reduce  the  effectiveness of the screen.  To
 eliminate these undesirable conditions,  the relative locations of pumps,
 screens and any upstream protrusions should be  carefully  studied.   The
 standards of the Hydraulic Institute recommend  screen to pump distances.
 However, these are based on pump performance criteria only.  Any radical
 departure from standard intake design should be modeled  to establish the
 actual screen velocity and the extent of any localized variations.


 Selection of screen Mesh Size

 The selection of screen mesh size is generally  based on  removal of trash
 that could clog condenser tubes.  A generally accepted rule of thumb for
 selecting  the screen mesh size is that the clear openings in the screen
 should be limited to  about half  the  diameter  of  the  heat  exchanger
 tubes.  The powerplant industry has become fairly standardized on a 0.95
 cm  (3/8")   mesh size (equivalent to 1.9 cm (3/4")  ID tubes)  even though
 longer condenser tubes are used in many  condenser designs.

 The effect of screen mesh size on the performance of  screens  is  quite
 significant  as  shown  in  Table  III-2.   The  data were supplied by a
 leading  screen  manufacturer.    The  table  shows   that   the   screen
 efficiencies  (ratio  of  net  open areas of the screen to total channel
 area)  decrease rapidly as the mesh size decreases.   The table also shows
that using alloy metals in place of galvanized metals will increase  the
 screen  efficiency  as  will the use of wider and deeper screens.   Alloy
metals are generally used to inhibit corrosion  in high salinity  waters,
 such as experienced in ocean cr estuarine intakes,  or in other corrosive
waters.    PVC screen mesh is also used.   The effective area is less than
                                25

-------
                           TRAVELING
CURTAIN WALL-x   RSH
                                           SUCTION PUMP
                                                   OF
                                             SCREEN
                                             ACTUALLY
                                             EFFECTIVE
               EFFECTIVE SCREEN AREA

                 FIGURE III-4
                     26

-------
NOTES:
I. VELOCITIES SHOWN  IN METERS/SET.
2 MEASUREMENT  MADE BETWEEN DEICING LOOP PIPE AND BAR RACKS
  (Kl MARCH 1970.
a MEASUREMENT  MADE DURING  THROTTLED CIRCULATING  WATER  FLOW,
  AT 30%  OPEN.
              UNDESIRABLE INTAKE WELL VELOCITY PROFILES


                           FIGURE III-5

                               27

-------
                                                       TABLE II1-2
NJ
CO
TRAVELING WATER SCREEN
EFFECIENCIES
Clear
Opening

cm.
0.32

0.48

0.63

0.95

1.28

1.58

Size
in.
1/8

3/16

1/4

3/8

1/2

5/8

Wire
Material

Alloy
Galv.
Alloy
Galv.
Alloy
Galv.
Alloy
Galv.
Alloy
Galv.
Alloy
Galv.
Selection
Diameter
cm.
0.12
0.16
0.12
0.16
0.12
0.20
0.20
0.27
0.27
0.34
0.27
0.34
in.
.047
.063
.047
.063
.063
.080
.080
.105
.105
.135
.105
.135
W&M
Ga.
18
16
18
16
16
14
14
12
12
10
12
10
0.61
(2)
.322
.334
.511
.445
.510
.459
.543
.488
.546
.496
.587
.541
0.91
(3)
.431
.361
.522
.457
.451
.469
.555
.498
.558
.506
.600
.552
1.22
(4)
.436
.365
.527
.462
.526
.474
.560
.503
.566
.512
.606
.558
Screen
1.52
(5)
.438
.367
.530
.465
.530
.476
.564
.506
.567
.515
.609
.561
1.82
(6)
.440
.368
.533
.467
.532
.478
.566
.508
.569
.517
.612
.563
Basket
2.13
(7)
.441
.369
.534
.468
.533
.479
.567
.509
.570
.518
.613
.565
Width Meter (Ft)
2.44
(8)
.442
.370
.534
.468
.534
.480
.568
.510
.571
.518
.614
.565
2.74
(9)
.442
.370
.525
.469
.535
.481
.569
.511
.572
.519
.615
.566
3.05
(10)
.443
.371
.536
.470
.535
.482
.570
.512
.573
.520
.616
.567
3.35
(11)
.444
.371
.537
.471
.536
.483
.571
.513
.574
.521
.617
.568
»
3.64
(12)
.444
.372
.537
.471
.536
.483
.571
.513
.575
.521
.618
.568
3.96
(13)
.445
.372
.538
.472
.537
.484
.572
.514
.575
.522
.618
.569
4.26
(14)
.445
.373
.539
.473
.538
.485
.573
.515
.576
.523
.619
.570
                 Alloy wire:  Copper, stainless, monel, etc. - greater corrosion resistance permits use
                              of smaller diameter wire, improves efficiencies.

-------
 for wire mesh for a given  screen  size.   Thus  if  mesh  velocity   is  a
 limiting  criteria   (rather  than screen  approach  velocity)  the  total
 screen area must be greater.

 Some work has been done  toward   establishing  screen  mesn   size   as  a
 function  of  the size of  fish to te screened.  Reference 24  reports the
 following empirically derived relationships:

    M = O.OU  (L-1.35)F; 5
-------
    0.0
   7.5
£


-------
these  reasons, most behavioral  systems have not demonstrated consistent
high level performance.

In addition, all behavioral systems require a passageway  to  allow  the
fish  to move away from the stimulus.  The location and configuration of
the required passageway is often more  difficult  to  develop  than  the
behavioral   barrier   itself.   The  following  discussion  traces  the
development of several of  the  behavioral  screens  in  an  attempt  to
establish their applicability in  intake design.


Electric Screens

The  basis  of the electric screen approach is described in Reference 18
and is shown in Figure III-7.  Immersed electrodes and a ground wire are
used to set up an electric field which repels  fish  swimming  into  it.
The important design parameters in electric screening are the spacing of
electrodes,  the  separation  between  rows  of  electrodes, the voltage
applied to the system, the pulse frequency, the pulse duration, and  the
electrical  conductivity  of  the  water.  Typical design parameters for
both test systems and full-scale systems are shown in Table III-3.   The
data  for  this  table  were  taken from Reference 13.  Most of the test
systems established by the former U. S. Fish and Wildlife  Service  (now
the  U.  S. Bureau of Sportfish and Wildlife)  were applied to repel (and
divert) upstream migrating fish  (adult  fish).   In  most  waters,  but
particularly  in brine or salt waters, conductivity can vary widely with
stream flows, tidal changes and storms, thus creating a need for  proper
adjustment of the electric screens to maintain the  electric  potentials
desired.

Typically,   salmon  respond to the screen in the following manner.  They
swim upstream against the  flow,  enter  the  electric  field  and  jump
violently back away from it, retreating several hundred feet downstream.
After  several  attempts and shocks they approach more slowly and follow
the angled electric field to the safe passageway provided.   If they  are
immediately  stunned, the downstream current will carry them safely away
from the  screen.

The electric screen has the advantage of flexibility and may r>e  applied
intermittently  during  time  of  need for intake protection.   The major
disadvantages of the  electric screening system are as follows:

         Cannot be used to screen downstream migrants.

         Cannot be used to screen a mixture of sizes and species  because
         of different reactions that are size  and species related.

         Cannot be used in esturarine or ocean waters  because of  high
         electrial losses.
                                  31

-------
                           LIN6 OU S|Et AM «.OT JOM
 A
                  PLAN
O.'C.
                ELEV. A-A
   TYPICAL ELECTRIC  FISH FENCE
                 FIGURE. III-7
                   32

-------
                                              TABLE  III-3




                                      ELECTRIC SCREEN APPLICATIONS




                                         SUMMARY OF  DESIGN  DATA
Location
*Pacif ic
Northwest
*Pacif ic
Northwest
*Pacif ic
Northwest
*Idaho
San Diego
(water intake)
Indiana (Power-
plant #1809}
N. Y. (Power-
plant #3608)
Specie
Squawf ish
Salmon
f ingerlings
Salmon
f ingerlings
Squawfish
Mixed
Perch
Fresh water
game fish
Barrier
Description
2 rows 0.46m (18") apart
5.0cm (2") 0 electrodes
in parallel rows @ 40°
angle to flow
5.0cm (2") 0 tubular
aluminum electrodes
@ 0.51m (20") spacing
in parallel rows
NA
NA
2 parallel rows 0.45m
(18") apart 0.30m (12")
spacing between electrodes
3.2cm (IV) <£ electrodes
@0.3m (12") spacing in
rows spaced 0.91m (3')
apart
Source
Voltage
(Volts)
60
NA
210
140
500-900
300-600
120
Pulse
Frequency
(Pulses/sec)
2
8
3-4
10
2-3
1-5
Continuous
Pulse
Duration
(Milli/sec)
10-30
40
20-40
50
10
NA
Continuous
Performance
good
68% diverted
82% diverted
80% diverted
effective for
large fish
effective
effective
Test systems

-------
         Can be dangerous to both humans and animals because o± the high
         voltages used.


The Fish and  Wildlife  Service  terminated  its  research  on  electric
screens in 1965.  Over fifteen years of concentrated research had failed
to  solve  many  of  the  major  problems of electric screening systems.
Several utilities have  investigated  the  problem  in  depth  and  some
research is still being conducted,but not much success has been shown to
date  for  downstream-migrant fish.  In summary, electric screens, while
not generally successful, may work in some situations.


Air Bubble Screens

The fish response employed by an air bubble screen  is  avoidance  of  a
physical  barrier.  In its simplest form, the bubble barrier consists of
an air header with equally spaced jets arranged to provide a  continuous
curtain of air bubbles over the entire stream cross section, as shown on
Figure III-8.

Historically  it  was  also  felt that the sensory mechanism involved in
utilizing the air bubble screen was entirely visual.  This  led  to  the
conclusion,  long  held,  that the screen was not useful at night.  More
recent findings of experiments  conducted  by  a  leading  manufacturer.
Reference  30,  tend to refute this belief.  Design and performance data
at two existing power stations are also  presented.   In  one  case  the
screen was successful and in the other unsuccessful.

The  laboratory tests referred to were conducted at the Edenton National
Fish Hatchery in North Carolina.  The experiments  were  conducted  with
striped bass and shad, 80mm to 250mm in length.

The  test  channel  used  is  shown in Figure III-9.  The results of the
tests are reported in Reference 30 and are summarized as follows.

    When the air bubble curtain was placed entirely across the 1.2m  (4')
    channel, the  fish would not pass through  in any of the tests, even
    when attempts were made to chase them through the curtain.

    Temperature does influence the  performance  of  the  barrier.   The
    tests  were  conducted  at  10°C,  <4.5°C  and 0.8°C  (50°F, 40°F, and
    33.5°F).  The bubble barrier was a complete  success  at  10°C(50°F)
    and  at  4.5°C(UO°F).   At 0.8°C(33.5°F) the fish were lethargic and
    simply   drifted  through  the  barrier  with  the   current.    This
    limitation  would  be shared with all systems which rely on swimming
    ability  of  fish to escape an intake.

    This particular bubble barrier  appeared  to  be  as  successful  in
    complete darkness as well as in daylight.  This tends to refute the
                                 34

-------
     AIR  BUBBLE SCREEN
TO DIVERT FISH FROM WATER INTAKE

       FIGURE iii-8
            35

-------
     vet.
PLASTK
TAUWL
\ 1
" \
feofc&U
PLACED
1.0 -
0,3-

S6CTIOU
J

^ FLovs/
)
>.2yi
(41)
TTP.
— PUMPS
                     PLAN
                                          0.29M TO
                                          CU" TO t&") DEPTH
                                           Op
 CHANNEL TO TEST  EFFECTIVENESS OF AIR BUBBLE SCREEN

          AT NORTH  CAROLINA FISH HATCHERY


                  FIGURE III-9
                        36

-------
    long held conclusion that these  systems will not work at night.    It
    also  indicates  that  sensory   mechanisms  other  than  visual   are
    involved, and that future work is required to define  fish   response
    to this type of situation.

    The air was injected through 0.08 cm  (1/32") round holes at   2.5   cm
    (1")   spacing.  At 5.0 cm (2") tc 7.5 cm  (3") spacing tne fish would
    pass between the rising bubble columns.

    When the bubble system was placed 5.0 cm  (2") off  the  floor,  fish
    would  not  pass under it.  When placed any further off the  floor  of
    the channel, the fish would pass unimpeded under the curtain.

A successful application  of  an  air  bubble  screen  was  reported   in
Reference  13.   The  system was installed at a powerplant intake  (plant
no. 5521)  on Lake Michigan in Wisconsin.   The  principal  fish   species
involved  was  the  Alewife,  a  variety  of  herring which is a neavily
schooling fish having a length between 15 and 20 cm  (6"  and  8").    The
plant  has  an  average  cooling water flow of some 18.3 m3/sec  (290,000
gpm).   The air bubble barrier extends across the intake channel, well  in
front of the intake structure in about 3.6 to 4.0m  (12' - 13')  of water.
The air bubble system consists of 2.5 cm  (1") diameter  PVC  lines  with
holes   drilled   on  10  cm  (4")   centers.   The  total  air   flow   is
approximately 0.047 m3/sec (100 cfm)  at 413.7 Ktt/m2  (60 psi).    The   air
is  supplied by a conventional compressor drawing 15,000 to 19,000 W  (20
- 25 hp) .   The optimum air flew was  measured at 0.01 m3/nun  (0.36  cfm)
per 0.3 m (1 foot) of air header at  413.70 KN/m2 (60 psi).

Prior  to  the  installation  of  the  air bubble screen, there had been
several shutdowns of the plant caused by schools of Alewives jamming  the
screens  and  shutting  off  the  flow  of  cooling  water.   Since  the
installation  of the screen,  there has been only one or two shutdowns of
this type during more than four years of operation.  The  major  purpose
of the air bubble screen is tc repel schools of fish rather than to stop
all  individuals.    The operation cf the bubble system at this plant has
been equally successful at night as in daylight.  The operation of  this
system was considered so successful that another utility located on Lake
Michigan  is  installing  a  similar  system  at  a new nuclear station.
(plant no. 5519)

The performance of a similar system installed at a major nuclear station
in the Northeast (plant no.  3608)  was exactly opposite of that described
above.  The species involved at this plant were  the  striped  bass  and
white   perch.    When  the  plant first went on line, there was a serious
loss of larger fish on the screens.  A series of modifications were made
in an  attempt to reduce the loss.   The modifications are shown in Figure
111-10 and consisted of the following:

    Removal  of eight feet of  the original curtain  wall  to  reduce  the
    intake  velocity.    Average  velocity  over  the  face of the screen
                                 37

-------
                                            c.w. PUMP
BUBBLE SCREEN INSTALLATION AT PLANT  NO.  3608
      TO REPEL FISH FROM WATER  INTAKE
              FIGURE 111-10
                       38

-------
    before the modification was about 0.30 m/s  (1  fps).   After  making
    the  change,  the summer average velocity was 0.18 m/sec  (0.60 fps),
    and the winter average velocity was 0.048 m/sec  (0.15 fps) .

    The installation of a fixed screen mounted flush with the front face
    of the intake to allow the fish to swim to  the  right  or  left  to
    escape entrapment.  This modificaticn also eliminated the entrapment
    zone  between  the  face  of  the  screen  and the existing vertical
    traveling screen.

    The installation of an air bubble system in front o± one of the four
    bays of the intake.  The bubble system  consisted  of  two  vertical
    rows  of  horizontal bubbler pipes.  The first row was located three
    feet in front of the intake and the second row was located six  feet
    in  front  of  the  intake.   Each  row  of  bubbler pipes has seven
    horizontal pipes in a four foot center to center spacing.   Air  was
    discharged  through 0.08 cm (1/32 inch)  opening at 1.3 cm (0.5 inch)
    center to center spacing.  The first tests were run with 0.424  m3/s
    (900 cfm)  of air which was far too large a quantity.  The surface of
    the  water  in  front  of  the intake rose by as much as one foot in
    violent  churning  action.   The  entrained  air  caused   vibration
    problems in the pumps.  The quantity of air was subsequently reduced
    to  0.189 m3/s (400 cfm) which is the design value used in modifying
    all bays.   The total cost fcr modifying both intakes at  this  plant
    in the manner described was approximately $1,000,000.

The results of these modifications are as follows:

    The intakes now impinge fish of a smaller size (50 to 100 nun)  rather
    than the larger sizes that were entrapped before the modification.

    The effect of the air apparently was to reduce the  number  of  fish
    entering  the bay equipped with the bubble system, but the number of
    fish entering the remaining three bays increased.

    During July 1972 tests, the test engineers were able to  discern  no
    improvements  in  fish  entrapment  during the daytime; at night the
    fish being trapped in  the  bay  equipped  with  the  bubble  system
    appeared  to  be  significantly  greater  than  in  the bays with no
    bubbler.

    The bubble barrier did appear to be effective in controlling ice  in
    front of the intake during freezing conditions.  This fact makes the
    bubble system attractive as a possible replacement for the hot water
    recirculation  systems which are currently being used to control ice
    at many existing installations.  The problems  associated  with  hot
    wa^er recirculation have been discussed in an earlier section.

In  summary,  the air bubble system may have some application at certain
types of intakes.  The system appears to be most effective in  repelling
                                   39

-------
schooling  fish.   However,  tne  mechanism  of  bubble screening is not
sufficiently well understood to recommend its adoption generally.


Behavioral Systems Employing Changes in Flow Direction

The propensity of most species of fish to avoid abrupt changes  in  flow
direction and velocity has been demonstrated on several occasions.  This
ability  of fish to avoid horizontal change in direction and velocity is
the principle on which the louver fish diverting system  is  based.   On
the  other  hand,  fish are generally insensitive to changes in vertical
flow characteristics.  This indifference of  most  species  to  vertical
changes  in  flow  regimen  is  the  principle upon which the "fish cap"
intake is based.

Louver Barrier

The principle of the louver diverter is illustrated  in  Figure  III-ll.
The  individual  louver  panels  are  placed  at  an angle o± 90° to the
direction of flow and are followed by flow  straighteners.   The  abrupt
change  in  velocity and direction form a barrier through which the fish
will not willingly pass if an escape  route  is  provided.   The  stream
velocity  is  shown  in  the figure as Vs.  Upon sensing the barrier the
fish will orient himself perpendicular to the  barrier  and  attempt  to
swim  away at a velocity Vf.  The resultant velocity VR carries the fish
downstream roughly parallel to the barrier to the bypass located at  the
downstream end of the barrier.  The controlling parameters in the design
of  the  louver  system  are  the  channel  velocity  VS,  the  angle of
inclination cf the barrier with respect to the channel flow  (10° to  15°
recommended)   and  the spacing between louver panels which is related to
the fish size.

Most of the current performance data on the louver design have come from
tests of two prototype installations at an irrigation intake operated by
the California Department of Fish and Game in the Sacramento-San Joachim
delta of California. 2*   The Delta intake is shown  on  Figure  111-12.
The  facility  is  designed  for a flow of 170 in3/s (6,000 cfs) , and was
tested at approach velocities tc the louver of 0.46 to 1.08 m/s   (1.5
3.5  fps)   with  bypass  velocities  of  1.2  to  1.6 times the approach
velocity.

The efficiency of the louver system  drops  severely  with  increase  in
velocity through the louvers.  For velocities of 0.46 to 0.61 m/s  (1.5 -
2  fps),  efficiency  was  61%  with 15 mm fish and 95* witn 40 mm fish.
When the velocity was increased to 1.08 m/s (3.5  fps),  efficiency  was
35%  for  15  mm  (0.6  in)  fish  and 70% for 40 mm (1.6 in) fish.  The
following conclusions were reached as a result of these tests.

    Efficiency increases markedly with fish size.
                                 40

-------
ClEAB. SPACE- BfcTweCU
                                                F]5V4 BYPASS
              LOUVER DIVERTER-SCHEMATIC
                           111-11

-------
DELTA FISH FACILITY PRIMARY CHANNEL SYSTEM
             FIGURE 111-12

-------
    Efficiency  increases with  lower channel velocities.

    Addition of a center wall  improves the efficiency, giving the  fish a
    wall to swim along if he wishes.

    Very careful  design  is   required  to  take  account  of  the  many
    variables,  such  as  bypass ratios, guide walls, approach velocity,
    louver angle, etc.   Each  application  would  most  likely  require
    extensive model testing to define optimum design parameters, for the
    species  of  concern at the temperature anticipated for each size to
    be dealt with.

    Individual louver misalignment did not have much effect.   In  fact,
    efficiency even improved with a deviation from the exact alignment.

    Swimming capacity is length related.

The major disadvantages of the fixed louver system are the following:

    The shallow angle of  louvers  with  respect  to  the  channel  flow
    requires  a rather long line of louvers which will increase the cost
    of the intake.

    The  louver  system  does  not  remove  trash.   A  second  set   of
    conventional  screens  are  required  downstream  of the louvers for
    trash removal.  The performance  of  the  louver  may  be  adversely
    affected in streams with a heavy trash load.

    A rather complex fish handling system is required to  safely  return
    fish to the water source.

    Water level changes and flow variations must be kept small to permit
    maintenance of the required flow velocity.

In an attempt to overcome some of these limitations, additional  studies
were  conducted  at  a major power station in Southern California  (plant
no. 0618).   Of the major fish types studied, the anchovy of about 130 mm
(5.2 in)  in length was the most delicate.   Another sensitive  fisn  (200
mm  (8.0  in)  in length)  was the queen fish.  The strongest and toughest
fish included white perch and croakers.   A sketch of the test  flume  is
shown  in  Figure  111-13  and results reported in Reference 32  were as
follows:

    The louver efficiency increased with flow up to  0.61  m/s  (2  fps)
    which was considered optimum.

    The bypass design is very important.   The  optimum  Bypass  velocity
    was  determined  to  be  1.08   m/s  (3.5 fps), a ratio of 1:1.5 with
    channel velocity.
                                 43

-------
T  .
AUGtt WAS
VAC. 16t>.

20°
                                                                  * TO ?i(
                                                     PAUEL- ALSO KAU
                                                         MESH
                                  PLAN



                      TEST FLUME AT  PLANT NO. 0618



                            FIGURE   III-13

                                     44

-------
    A 2.5 cm (1")  louver spacing  gave  good  results.   Increasing  the
    louver spacing to 4.5 cm  (1.75") reduced efficiency significantly.

    The louvers should have a 20° or less  angle  with  flow  direction.
    Increasing this angle markedly reduced louver efficiency.

    The louver system worked as well at night as during the daytime.

The experience gained in these tests is  being  used  to  design  a  new
intake  for  a major nuclear installation  (plant no. 0629).  A sketch of
this intake is shown in Figure 111-14.

The intake employs the louver principle described  above.   The  louvers
are  mounted  on  frames  similar  to  the  conventional  water screens.
Instead of the fixed louver system, the louvers are rotated in a  manner
similar   to  a  traveling  bar  screen  used  in  municipal  wastewater
treatment.  A water jet system washes any material from the  louvers  as
it  passes  over  a  standard  trash  trough.   Behind  these vertically
traveling louvers is a standard vertical traveling fine  screen  similar
to  that  used  at  most powerplant intakes.  The louvered frames are so
mounted that the front of the frame is flush with the  walls  supporting
the  entire  mechanism  so that fish may move unimpeded down the face of
the louver vanes.   The louver vanes serve as trash racks.

A very important element of the intake is the guide vane system upstream
of the louver faces.  These vanes insure that the  flow  does  not  turn
before it reaches the louver.

Fish  moving  down  the  face of the Icuvers enter a bypass.  The bypass
itself has a unique fish lifting system, Figure 111-15, which litts  the
fish up several feet, where they can be dropped into a channel lor their
return  to  the  sea.   Supplementary  water  is  also  pumped into this
channel.

A very substantial amount of model testing was required to develop  this
intake.  The model work included the test flume, the test set up for the
lifting  basket  and  all  its  flow  mechanisms,  the  detailed  intake
structure itself and the detailed bypass system.

While it will be several years before performance data  on  tins  intake
will be available, its successful operation would represent a large step
forward  in  intake  design.  The louver principle has been demonstrated
both in model and in large prototypes  and  should  have  a  significant
impact on future design of intakes.  The cost of installing tins type of
intake will be substantially higher than those of a conventional intake.
                                 45

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                         COUVEUTlOUAL
                          "BAR

                        B.W6C.
                                       K.  V
                                            X
                              P L
              INTAKE  STRUCTURE  -  PLANT NO.  0629,


TO DIVERT FISH BY LOUVER SCREENS AND RETURN  THEM DOWNSTREAM

                       FIGURE HI-14
                          4.6

-------
      i
                    "
                                     VJ
                    A
I5CM
               2.1M
                               SI

                   PLAN
          to
                                        3
                                        0
                                           seen
                 BASKET
                SECTION
FISH ELEVATOR FOR FISH BYPASS -  PLANT  NO.  0629

               FIGURE 111-15
                  47

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"Velocity Cap"  Intakes

The  operation  of a velocity cap is shown in Figure 111-16.   It is based
on laboratory studies which shew that fish do not  respond  to  vertical
changes  in  direction,  whereas  they  show  a  marked ability to avoid
horizontal changes in velocity.  By placing a cover over the  top  of  a
intake,  the  flow*'pattern entering the pipe is changed from vertical to
horizontal.  As shown in the illustration, the cap has a rim around  its
edge  to  prevent  water  sweeping  arcund  the edge and to provide more
complete horizontal flow at the entrance.
                                                                       a
Velocity caps have been used since 1958, when one  was  installed  at
ocean-sited power station in California (plant no.  0623).  Several other
plants  in southern California have adopted the concept since then.  One
problem with the utilization of the velocity cap is that it is difficult
to inspect, since it is under water.  Frequently, the only sign that the
cap is not working properly is an increase in fish on the screens.


Other Behavioral Systems

Other behavioral mechanisms have been experimented with  in  conjunction
with  fish  diversion.  These include sound barriers, light barriers and
several types of fish attraction  systems.   The  types  of  experiments
conducted in regard to these systems have generally been more cruae than
those  discussed  earlier.  Consequently, the results are generally less
conclusive indicating that considerably  more   formal  investigation   is
required before these sytems can be fully evaluated.


Light Barriers

The  same test flume  shown  in Figure 111-13 and  discussed in Reference  30
was   also  used   to   test  a  light barrier  system.  Upon approaching   a
1-iqtr- barrier placed  across  the full width of the  flume  for  the  first
tim«" during  the  rest,   the   fish would mill  around for 3 to  5  minutes
befor-  passing through.  On  subsequent  trips   around  the  flume,   they
would hesitate less  and  less until  the  time  for each  circuit  was  reduced
^c that which existed without  the  light source. This indicates that the
 fish rapidly  become acclimated   to  light  which  renders  such  a  barrier
us-less.   O^her  experiments  with   the   same   apparatus   using  light  in
conjunction  with   a bubble  curtain were  also unsuccessful.   It was con-
 cluded  from  these  test  that  light  had  no  effect   from   a  practical
 s^-ancipo^r.-*-.    As   far as   could   be   determined,   there are  no existing
 ir^a'kf-s~wh~re  a  xight barrier  is  functioning successfully.    Light  also
 has   -h^   adverse  effect  of attracting fish under certain  circumstances
 and  has resulted in the  complete  shutdown of plants.

 Souia Farriers

 Fish have been shown to  respond to sound of  high  intensities  and  low
 frequencies,   but  become  accustomed  to constant sound levels.  It has
                                   48

-------
VD
            Velocity Distribution Without  Cap
Velocity Distribution With  Cap
                                 OPERATION OF  THE  VELOCITY CAP




                                        FIGURE 111-16

-------
been shown that minnows respond  to  frequencies  up  to  6,000  Hz  and
catfish  to  13,000  Hz  or  only  slightly less than the 15,000 Hg band
considered normal for humans.   Cther fish respond to frequencies  up  to
only  1000-2000 Hz and are less sensitive to sound intensity.   This high
variability to sound among different species is a major drawback to this
type of system.

There have been many attempts  to direct fish  around  intake  structures
using  sound barriers.  A recent installation at a major nuclear station
in Virginia (plant no. 5111)  employed reck and roll music  broadcast  at
relatively  high  intensities   under  water.   This  type  of   music was
selected because of its multi-frequency nature and because  it  is  non-
repetitive.   The conclusion was that the system appeared to be at least
partially effective.  However, due to the many  species  and  and  sizes
involved  and  the  diversity   of responses, it was decided to install a
mechanical system to reduce the  fish  entrapment  problem.   The  sound
system  will  continue  in  use  while  the  mechanical  system is being
installed.  A discussion of the proposed mechanical system is  contained
in another section of this report.

Applicability of Behavioral Screening System

In   summary,   none   of   the  behavioral  systems  have  demonstrated
consistently high  efficiencies  in  diverting  fish  away  from  intake
structures.    The  systems  based  on  velocity  change  appear  to  be
adequately demonstrated for particular locations and species,   at  least
on  an  experimental  basis.    More  data  on  the  performance of large
prototype systems at powerplants will  te  required  before  the  louver
system  can  be  recommended for a broad class of intakes.  The velocity
cap intake might be considered for offshore vertical  intakes  since  it
would add relatively little to the cost of the intake and has been shown
to be generally effective in reducing fish intake to these systems.

The  performance  of  the  electric screening systems and tne air bubble
curtains appear to be quite erratic, and the mechanisms governing  their
application  are  not  fully  understood at the present.  These types of
systems might be experimented with in  an  attempt  to  solve  localized
problems  at  existing  intakes,  since the costs involved in installing
these systems is 'relatively small.

No  successful  application  of  light  or  sound  barriers   has   been
identified.   It  appears  that fish become accustomed to these stimuli,
thus  making  these  barriers   the  least  practical  of  the  available
behavioral systems on the basis of current technology.
                                 50

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Physical Screening Systems

All cooling water intake systems employ a physical screening facility to
remove  debris  that  could  potentially clog the condenser tubes.  Such
facilities range from simple stationary water screens  to  filter  beds.
This sub-section will consider only mechanical screening mechanisms.  In
general,  these  mechanical  screens  have been developed to protect the
powerplant from debris, rather than to protect aquatic life.

In other sections intake  facilities  are  reviewed  as  a  whole,  with
further  consideration  of the installation and operation cf some of the
mechanical systems discussed here.  Also reviewed in other  sections  is
the  important  area  of  fish repulsion systems based on the oenavioral
characteristics of fish.

The following mechanical screening devices are the principal types which
are either in common use or have been suggested for  use  in  powerplant
circulating water systems, both in the United States and abroad.

    1.  Conventional vertical traveling screens

    2.  Inclined traveling screens

    3.  Fixed screens

    4.  Perforated pipe screens

    5.  Double entry, single exit vertical traveling screens

    6.  Single entry, double exit vertical traveling screens

    7.  Horizontal traveling screens

    8.  Revolving drum screens - vertical axis

    9.  Revolving drum screens - horizontal axis

    10. Rotating disc screens

Most  of  the  types  of  revolving  drum  and rotating disc screens are
commonly used in powerplants outside the United  States  and  have  been
supplied  by  European  manufacturers.   They  have not been used in the
United States, with the exception of a few  experimental  screens  which
will be discussed.


Conventional Vertical Traveling Screens

By  far  the  most  common  mechanically  operated  screen used in U. S.
powerplant intakes is the vertically rotating  single  entry  band  type
                               51

-------
screen  mounted  facing the waterway.  A catalogue cut of this screen is
shown in Figure 111-17.  Figure 111-18 is a  schematic  drawing  showing
the principal operating features.

The screen mechanism consists of the screen, the drive mechanism and the
spray  cleaning  system which requires a means for disposal of the waste
materials removed from the screen.  The screen is attached to an endless
chain belt which revolves in the vertical plane between  two  sprockets.
The  screen  mesh  is  usually  supplied  in individual removable panels
referred to as "baskets" or "trays".  A continuous band screen  is  also
available  but  is  not often used.  The entire assembly is supported by
two or four vertical steel posts.   Longer  and  wider  screens  usually
require the stronger four post box structure for support.

The  screen washing system consists of a line of spray nozzles operating
at a relatively high pressure 550 to 827 KM/m*   (80  -  120  psi).   The
washing system may be located at the front or the rear of the screen, or
both.   The  usual  location is in front as shown in Figure 111-18.  The
quantity of water required for spray cleaning is in the order  of  0.372
m/s  (98.42  gpm)  per  meter   (3.28')   of screen width.  It is supplied
either by booster pumps taking suction from the circulating  water  pump
discharge  or  by  separate  vertical  shaft pumps.  The disposal of the
debris is usually accomplished by discharging  the  screen  wash  waters
from individual screens to a common disposal trough located at the floor
on  which  the  screen is mounted.  The trough drains eitner to a debris
storage compartment or directly back  to  the  waterway.   If  a  debris
storage  compartment  is  used,  the  water is allowed to drain from the
bottom of the compartment  and  the  remaining  refuse  is  periodically
removed  to  a  land disposal area.  Both the drive shaft and the screen
wash system are enclosed in a removable housing  to  protect  the  drive
components and to contain the high pressure water spray.

The  conventional  vertical traveling screen has several advantages.  It
is a proven off-the shelf item and is readily  available.   It  performs
efficiently  over  a  long  service  life and requires relatively little
operational and maintenance attention.  It is applicable to  almost  all
water  screening  situations.  It is available in lengths up to about 30
meters (1001) and 15 cm  (6") increment widths up to 4.26  meters   (14').
The  system  adapts  easily  to  changing  water  levels.  The screen is
relatively easy to install.  Major components of the  system,  including
supports, baskets, drive mechanisms, and spray systems are standardized.
Special  materials  for  corrosion protection and greater durability are
also available.

The system as presently used has several undesirable features  that  can
cause  adverse  environment  impact.  The most important of these is the
fact that any fish impinged on the mesh of the screen will  probably  be
destroyed.   This  effect results from both the design of the system and
the way it is operated.   Most  traveling  water  screens  are  operated
intermittently, not continuously, and fish are pinned against the screen
                                  52

-------
Head
terminal
Electrofluid
Motogear

Spray pipes
and nozzles
                                               Head
                                               sprocket
                                          Foot shaft
         CONVENTIONAL VERTICAL TRAVELING SCREEN
                       Figure 111-17

                          53

-------
                              opee-AyiUG  oecK
                                          ^
CONVENTIONAL VERTICAL TRAVELING SCREEN




           FIGURE 111-18
                54

-------
for extended periods of time.  When the screens are rotated the fish are
removed from the water and then subjected to a high pressure spray, both
of  which  may  be  lethal.   Any  fish  surviving these hazards will be
destroyed in the subsequent refuse disposal operations, if the refuse is
not returned to the waterway.

The  above  discussion  suggests  the  following  possible  avenues  for
correcting  some  of  the  environmental  defects  of  the  conventional
traveling water screen:

    a.  reduce impingement time by continuous operation of the screen.

    b.  provide a path  for  rapid  and  safe  return  of  fish  to  the
    waterway.

    c.  mount the screen so as to provide fish escape passages to either
    side,  a  feature discussed in the section concerning overall intake
    design.

The current design of traveling water screens and the screen  structures
themselves  would  not  require  radical  changes to adopt the first two
corrective measures.  Several intake designers and screen  manufacturers
have  proposed modifications of this type in past years and at least one
major nuclear station (plant no. 5111) is modifying its  screen  baskets
and   operational   procedures   to   provide  fish  protection.   These
modifications are discussed in a subsequent portion of this report.

Inclined Screens

Two basic types of inclined screens are available.  The first, shown  in
Figure  111-19,  is  merely  an  adaptation of the conventional vertical
traveling screen.  It is used at installations where the debris  loading
is  extremely  heavy  and is of a nature that does not readily adhere to
the screen.  The downstream inclination of the screen  (usually  10°  to
vertical)   allows  debris falling off the lip of one basket to be caught
in the following basket rather than  falling  back  into  the  waterway.
Also, by inclining the entire screen frame, debris being lifted from the
channel  is  supported  more  fully by the ascending basket lips and the
backward tilted  screen  wire.   This  type  of  screen  thus  might  be
advantageous  in  insuring  more  rapid  removal  of fish, shellfish and
jellyfish from the waterway for subsequent bypass  as  discussed  above.
The  number  of  installations using this screen is relatively small and
the system has the same advantages and  disadvantages  as  the  vertical
traveling screen.  The cost of this screen would be slightly higher than
that of the vertical screen, due to the longer screen well required, the
use  of  two  rows  of spray nozzles and other minor variations from the
conventional vertical screen.

The second type of inclined screen has been designed  specifically  with
fish  protection in mind and has significantly different design features
                                   55

-------
tn
                                   TRAVELING WATER SCREEN

                                      FIGURE 111-19
                                                               1
!i
vO|
u>u-
DO"
                                                                          •secyiouA-A

-------
 than the  conventional vertical  traveling water   screen.   This  type  of
 system is shown  in Figure  111-20.

 It  is  still in the experimental  stage, but such a  screen has been used
 successfully in Canada to  divert  downstream  migrating  fish  and  its
 performance  is  reported  in Reference 21.  This system employs a fixed
 screen inclined downstream at an extreme angle   to   the  vertical.   The
 rear portion of the screen is bent horizontally  over the fish collection
 trough.   The  screen  is  cleaned by a continuous chain flight conveyor
 similar to that used in conventional water and wastewater  sedimentation
 practice.   The  differences  are  the orientation of the collector above
 the screen and the conveyor flights which are made of  a  pliable  brush
 material  rather than solid metal.  By orienting the screen and cleaning
 mechanism in this manner the fish  can be slowly  herded up the screen and
 kept immersed in water until it is dumped gently into me bypass trough.
 This design avoids many of the  pitfalls  of  impingement  on  vertical
 traveling screens.  The fish is not really impinged  in the real sense of
 the  word.   He  never  leaves  his  normal  habitat of water and is not
 subjected to the extreme pressures  of  the  conventional  system  spray
 wat er.

 The  system  has  some  important  limitations.  It  is very sensitive to
 fluctuations in water level, since the  water  level variation  at  the
 horizontal  section  of  screen must be limited  to a few inches; a level
 control mechanism such as  the slide gate shown in Figure 111-20 is  thus
 required.  Another disadvantage is that the cost of  the intake structure
 for  this  type of screen  would be significantly increased.  The shallow
 angle of placement with respect to the incoming  flow causes  the  length
 of  the intake channel to  be several times longer than that required for
 the vertical traveling screen of the same screening  capacity.

 The application of this type of system, as well  as several others to  be
 discussed,  is  limited  in  many  areas  because  of the regulations of
 cognizant water quality control agencies.   Reference  here  is  to  the
 common  policy  which  prohibits   the subsequent discharge of any debris
 after it has once been removed from the waterway.

 As can be seen from Figure III-20, the method of diverting fish  to  the
 bypass  trough  also  allows for the discharge of the debris back to the
 receiving water.   Prohibition of this debris discharge would also result
 in the prohibition of safe fish return.  it is apparent  that  the  same
 comment  applies to the discharge from the conventional traveling screen
 previously discussed.   However, in certain cases fish can  be  separated
 from the debris.


 Fixed Screens

This  term is applied  to a number of different types of screens, some of
which are permanently  anchored below the waterline of intake  structures
                                  57

-------
30
                        ,

              SHOTT€|LHO»ST
                             Q*&&ys2~::.r.-.-'.'
.1 ..^-...-x -r.! > < ?
•.-."•.•---•-:•- - •  -
                                                       AMD
                                INCLINED PLANE SCREEN WITH  FISH PROTECTION



                                              FIGURE  IH-20

-------
and  others,  the more common, which can be moved but are not  capable of
continuous travel.  Taken together  "fixed"  screens,   (or  "stationary"
screens),  constitute  the  second  largest  group of physical screening
devices  presently found in  powerplant intakes.  Examples of two types of
screening systems in this category are shown in Figure  C-II1-21.   Note
that  both  types of screen would not be used at the same intake and are
only shown on the same figure for convenience.

The first type of screen is mounted upstream of the  pumps  in  vertical
guides   to  allow them to be removed to a position above the water line.
Figure III-21 shows a relatively sophisticated installation wherein  two
rows  of  screens  are provided to permit one to remain in service while
the other is being changed.  in addition, each row is divided  into  two
sections  in  a manner which allows removal of the lower section without
removal  of the upper section.  Some debris and fish can be  sucked  into
the  pump during the process of changing screens.  The screen guides are
sometimes extended above the deck to hold the raised  screens  in  place
for  cleaning.   Figure  III-22  is a sketch showing typical fabrication
details  of such a screen.

Another  fixed screen type involves attaching a cylindrical screen to the
pump suction bell, also shown in Figure 111-22.  The  cleaning  of  this
type  of screen is very difficult; it may be done by dewatering the bay,
with the use of divers or by backwashing through the pump,  all  methods
being unsuited to the continuous pump operation required at powerplants.

The  bulk  of fixed screens are found on smaller and older plants.  Some
newer plants located on water bodies that  have  small  debris  loadings
have  also  installed  this  type  of screen.  The only advantage over a
conventional traveling water screen is a savings  in  the  cost  of  the
mechanical  equipment  and  in maintenance costs for the screens, screen
drives,  spray wash  pumps,  etc.   Operating  costs  may  be  higher  if
frequent manual cleaning is required.

Fixed  screens  have  serious  drawbacks,  both  from  a plant operation
standpoint and an environmental standpoint.  First,  operators  must  be
immediately  available  to  raise  and clean the screens when a limiting
head loss occurs (as  signalled  by  a  differential  level  alarm,  for
example).   Secondly,  no  matter how light the debris load may normally
be, the possibility always exists that a sudden  heavy  debris  or  fish
load  could completely clog the fixed screen, causing plant shutdown and
possibly collapse of the screens  and  circulating  water  pump  damage.
Because  of  these  factors  many fixed screens originally installed for
economy reasons have subsequently been  replaced  with  traveling  water
screens.

From  the  environmental  standpoint  the  fixed  screen involves longer
impingement periods between cleaning cycles and increased damage to  the
impinged  fish  because  of  greater  velocities across the increasingly
clogged screen.   The crude methods employed to clean  fixed  screens  is
also damaging to fish.
                                  59

-------
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                                                                             t Jl»3.t.V-
                                                                                   PET U L   HO.
                                   PJXED (STATIONARY) SCREEN DETAIL

-------
           HOIST - »
        STRUCTURE
   "FIXED" SCREENS
    2 SETS OF 2)
                                CIRC. WATER
                                    PUMP
                             —SERVKE
                             'WATER PUMP
•TRASH RACK
  5TOPLOG5
ALTERNATIVE FIXED
SCRFETN FOR RELATIVELY
SMALL PUMPS
                FIXED (STATIONARY) SCREENS
                     (SCHEMATIC ONLY)

                     FIGURE  111-22
                           61

-------
Perforated Pipe Screen

Figure  III-22A  shows  a  type  of  "fixed screen" with characteristics
significantly different from the fixed  screens  discussed  above.    The
screen consists of a perforated pipe placed in the waterway and oriented
in  such a manner that the passing current will sweep debris downstream.
There are several installations of this type in service.  They  have  to
date  been  designed for debris handling service without respect to fish
protection.   However, it appears quite possible that this type of screen
may be very effective in reducing fish mortality.

Model tests are currently underway for  one  nuclear  powerplant  makeup
water  intake  to  develop optimum perforation velocity, size and shape,
all specifically to provide maximum fish protection.  Additions  to  the
inside  of  the  pipe,  such  as  sleeves,  may be mads to produce equal
velocities through the perforations.  Very low approach  velocities  can
be  achieved  with a reasonable total length of perforated pipe, divided
into several individual  pipes  if  necessary.   In  this  manner  large
quantities  of  water  may  be handled at what may be substantially less
cost and greater  fish  protection  effectiveness  than  presently  used
conventional screens.

Backwash  provisions  may  be included as shown in Figure III-22A,  but a
review of existing installations has  indicated  that  these  provisions
have not been extensively needed.

Double Entry, Single Exit Vertical Traveling Water Screens

Figures  111-23, 111-24, and IJI-25 show two types of installation for a
vertical traveling screen which takes water from both sides  and  passes
it  out  through one end of the screen, thus doubling the screening area
for a given width of screen.  Although this unit appears similar to  the
conventional traveling screen there are significant differences.

Figures  111-23 and 111-24 show the most common mounting of this type of
screen.  The unit is turned so that the approach flow is parallel to the
faces of the screen.  It is mounted in a concrete  screen  well.   Water
enters  through  both  the ascending side and the descending side of the
screen, thus utilizing both sides  for  water  cleaning.   For  a  given
theoretical mesh velocity the screen will have twice the capacity of the
conventional  screen.   There  is no possibility of debris carry over to
the pump side, since incomplete cleaning will simply result in returning
the debris to the incoming water for recycling.

There are several drawbacks to this type of installation,  however,  and
from both the operational and environmental points of view it appears to
be inferior to the conventional screen.  Some of these objections are as
follows:
                                 62

-------
PERFORATED PIPE SCREEN
      RIVER CHANNEL)
  FIGURE IH-22A

        63

-------
  Guide sprocket
  with chain
  tensionmg
  device, adjustable
  with screen
  running
 Wash water
 supply
 connection
Non-corrodible
main chains
30,000 Ib breaking
load. Low friction
Nylon rollers
   Screen slides
   into locating
   members
   and can be
   withdrawn
   bodily if
   required
                      OUTLET
                      Screened
                      water
                                DOUBLE ENTRY, SINGLE EXIT
                               VERTICAL TRAVELING SCREEN
                                        Figure  111-23
Wash water
and debris
chute, tc
drain.
                                                                               Driving gear
Driving sprocket
  Double row of
  wash water
  fan-|et nozzles
  in splash proof
  casing
                                                                               Main frame 'H'
                                                                               members, with
                                                                               guide channels
                                                                               and wearing
                                                                               strips for chain
                                                                               rollers
Non-corrodible
screen panels
with deep buckets
for lifting debris,
replaceable without
dismantling
main chains
                                                                              Fabricated steel
                                                                              supporting feet,
                                                                              chain-roller guide
                                                                              paths continued
                                                                              in large radius
                                                                              round base
                       64

-------
VERTICAL
TRAVELING
SCREENS
      A
                       INFLOW
                                             •4 CIRC. WATER
                                                PUMP5
                                          4- BLANK PLATC
                                                   f
   VERTICAL  TRAVELING
        SCREEN' 	
         FACE
I    I
                     \
                                 SPR4Y 5VSTEM
                                 TRA5W TROUGH
                                   5CREEM  FACE
                                  ^DOUBLE  ENTRY, SINGLE EXIT
                                   VERTICAL TRAVELING SCREEN
                                      (SCHEMATIC ONLY)
                                       FIGURE 111-24
                   SECTION A-A

                     65

-------
 DOUBLE E^'TRY SINGLE EXIT
VERTICAL TRAVELING SCREEN
   OPEN WATER SETTING

     Figure 111-25

           66

-------
    a.   If  the double entry screen is to handle twice the flow volume,
    as suggested by the manufacturers, it will have to handle  twice  as
    much  debris as the single entry screen.  At the same rate of screen
    travel debris clogging will occur much more quickly.

    b.  The clean screen face is first introduced to  the  flow  at  the
    water  surface.  The debris picked up by the descending baskets must
    then be pulled down and  through  the  boot  section.   Debris  thus
    collected  on  the  descending  run blocks the screen for the entire
    cycle.  This is  in  contrast  to  the  single  entry  screen  which
    presents  a  clean basket to the flew and usually does not encounter
    the majority of the debris until just before it  lifts  out  of  the
    water.

    c.   Since  head  loss  increases  en  an exponential basis with the
    degree of blockage of the screen wire, the  dual  flow  screen  will
    have  to  be  designed  to operate under higher head losses.  Higher
    head loss design requires both a structurally stronger screen and  a
    higher horsepower drive.

    d.   The  double  entry  screen mounted as in Figure 111-22 requires
    abrupt changes in water flow direction  as  it  passes  through  the
    screen.  This will result in nonuniform flow across the screen face,
    with  high  localized  velocities,  additional  system head loss and
    possibly enough turbulence to upset pump operation.

    e.  The common setting shown in Figure 111-22 does not  provide  any
    escape  route  for  fish other than to swim back out of the channel.
    Definite fish trap areas result at both faces of the screen.

This type of screen is frequently used outside the United States and  is
also offered as a standard item by one U. S.  manufacturer.

Figure  III-25  shows  an environmentally promising alternative mounting
for the double entry screen.  Here the screen is mounted on  a  platform
and is surrounded by water on all sides.

There is no confining concrete structure which might trap fish.  This is
a major asset from the point of view of fish protection.  Trie screen has
some of the mechanical drawbacks of the mounting shown in Figures 111-23
and  111-24.  In addition, the pump suction piping will cause non-uniform
flow through the screen mesh since abrupt flow  direction  changes  must
take place to get the water to the pump.  Not shown in Figure 111-25 are
trash  racks  and  associated structure which will probably be needed to
protect the screen from heavy debris.   Even with such added  facilities,
however,  the total cost of the screen and pump installation for the open
type  mounting  may  well  be less than for an installation using either
conventional traveling screens  or  the  screens  mounted  as  shown  in
Figures 111-23 and 111-24.
                                 67

-------
It  might  be  noted here for reference that the principle of the "Open"
type of screen mounting typified in Figure 111-25 is also a  feature  of
one  of  the  alternative  mountings  of a European drum screen shown in
Figure 111-38, the pump suction piping  is  similarly  attached  to  the
screen  frame  itself,  allowing open water to surround the screen, thus
avoiding fish trap areas.


Single Entry, Double Exit Traveling Screens

Figures 111-26 and 111-27 show a screen type  which  reverses  tne  flow
path  shown  for  the  double  entry screen previously discussed.  Water
enters through an opening in one side of the screen frame and  exits  to
both  the  right  and  left  through the ascending and descending screen
faces.  Debris is removed from the screen baskets into a trough  on  the
inside  of  the  screen  by both gravity action and sprays.  There is no
possibility of carrying debris over into the "clean" side of the system.
None of these European designed double  exit  screens  is  presently  in
operation  in  the United States, but they are en order for at least two
major U. S. powerplants.

The advantages and disadvantages of this design are similar to those for
the double entry  screens  previously  discussed.   One  potential  fish
protection feature of the screen shown in Figure 111-27 is a substantial
debris,  water  and  fish  holding trough for each section of individual
curved screen basket.  Fish might be less likely  to  flip  out  of  the
trough  back into the incoming water and thus would not be "recycled" in
the manner which is objectionable on unmodified  conventional  traveling
screens.

Neither this screen nor any of the ether vertical traveling screens were
developed with fish protection in mind.  Thus they have tne inherent and
obvious  environmental  drawbacks  which  have  been  highlighted in the
previous discussions.


Horizontal Traveling Screen

Figure 111-28 shows the principle of the horizontal traveling screen,   a
device  specifically developed to protect fish.  It elicits a behavioral
response from the fish similar to the  louver diversion system  discussed
elsewhere  in this report.  The horizontal screen, which is still in the
experimental stage, is the single major advance in mechanical  screening
technology   in the last  decade.  It was initially developed by the  U. S.
Fish  and Wildlife Service in  Oregon.   Later  financial   and  technical
support  has  come  from  several  utilities  and  a  commercial   screen
manufacturer.

As  shown schematically in Figure 111-28, the horizontal traveling  screen
rotates horizontally at  a sharp angle  to the incoming water  flow.   The
                                  68

-------
SINGLE ENTRY,  DOUBLE EXIT
VERTICAL TRAVELING SCREEN

     FIGURE  111-26

             69

-------
                             INFLOW


TRASH TROUGH-y


f

t •' • *• •
y

' C3
' * '-a -


<: - ° f~ ?• ' "'



-^^~
XREEN
1 1 i ...

N^ ' -* • . ^e • •- . •

.
D
0
*> «.
._..y ..

« o 
-------
HORIZONTAL TRAVELING  SCREEN
     (SCHEMATIC ONLY)

      FIGURE 111-28
            71

-------
principle  is  to guide fish to a point where a bypass channel can carry
them to safety.   It has been very effective.  Upon sensing the screen, a
fish will orient himself perpendicular to the screen and attempt to swim
away from it along VR.  This he is able to do since the component of the
channel velocity opposing his effort (VR)  is small.  In this orientation
the fish is swept downstream  along  the  face  of  the  screen  by  the
component  of  channel  velocity  which  is parallel to the screen (VS).
When he reaches the end of the screening leg he moves  into  the  bypass
channel for safe passage back ro the waterway.  The size of fish that is
effectively screened can be reduced by reducing the angle of inclination
of  the  screen with respect to the channel flow direction.  However, as
this angle is reduced the size of the screen increases for the same flow
rate, increasing the cost of the intake.  Some small percentage of  fish
will  become  impinged  on  the screen, but they will be released at the
bypass and will also not be pressed as tightly  against  the  screen  as
they would be in a vertical screen.

The  latest experimental version of this screen (designated Mark VII) is
shown schematically in Figure III-29.  It is located on the Grande-Ronde
River near Troy, Oregon and was designed in  cooperation  with  a  major
commercial   screen   manufacturer.    Although   this  screen  and  its
predecessors  have  undergone  extensive  tests  the  manufacturer   and
knowledgeable  intake  designers  estimate  that  it  is  at  least  two
generations of experimentation away from installation at a  major  steam
electric  powerplant.   Application of this screen to a large industrial
intake at this time would require extensive and costly research.

Some of the problems  are as follows:

    a.  The screens operate continuously and at very high rates of speed
    compared with vertical  screens.  For the Mark VII screen the rate of
    travel is variable from 0.4 to 1.2 m/s  (80 - 240  fpm)  as  compared
    with  a  usual maximum  of  0.05 m/s  (10  fpm) for the vertical screen.
    All components of the mechanism are thus  subject  to   severe  wear.
    Reliable, long life components have not been developed.

    b.   Water   level  differential  due  to clogging must  be limited to
    avoid collapse of the screen.  Either the pumps must  be tripped  to
    stop  flow   or  the  screen  panels must be designed  to spring open.
    This latter  solution was used  in the Mark VII  screen.   If the panels
    thus open they  will  release  fish  and  debris  and  supplementary
    conventional traveling screens  will  be required downstream of  the
    horizontal  screens to protect  the cooling water system.

    c.  The horizontal  screen  cannot accommodate significant  variations
    in   water    depth  in  its  present   stage  of  design.    Effective
    performance  hinges on suitable approach water  velocities.
                                 72

-------
   :SEAL
   FISH AND
   .DEBRIS  BYPASS
                    -PANELS  NORMALLY
                     OPEN ON BACKSIDE
  PANELS IN EMERG
-OPEN POSITION
     PASS DEBRIS
 \   OVERLOAD)
SCREEN  WIRE--
0-07/ CW DiA-
*8 MESH - 60% OPEW
NET 35% OPEN FOR
OVERALL SCREEN
I STRUCT  ELF/1.
                                                SCREEN  1-9
                                                HIGH, WATER
                                                DEPTH
RATE  OF SCREEN
TRAVEL, V:
0-4 TO 0-7  m/s
                                                 fO HP MOTOR
           MARK VII HORIZONTAL TRAVELING SCREEN
                     (SCHEMATIC ONLY)

                    FIGURE 111-29

                          73

-------
    d.  The maximum screen panel height is about 6.1  meters   (14  feet)
    due  to  the  same  general  structural limitations that control the
    maximum width of a vertical traveling screen.

    e.  Due to lack of gradient in the  incoming  water  screen,  it  is
    difficult  to  obtain  sufficient bypass velocity without the use of
    supplementary pumps in the bypass system.

    f.  Debris as well as fish must be handled  on  the  bypass  system,
    thus required additional water cleaning facilities.

    g.   Screens  would  have  to be redundant to permit continuous full
    load operation during screen maintenance shutdowns.  The size of the
    installation will thus become very large and costly compared with  a
    vertical screen facility.

    h.   Debris and bed load tend to jam lower tracks.

Figure 111-30 is a schematic version of  a  possible  variation  of  the
horizontal  screen setting.  This location and orientation would utilize
the velocity of the passing water to carry the fish to safety and remove
trash.

The principle of angling the water cleaning facilities to  the  incoming
flow  is further developed in ether sections, with respect to the louver
system of behavioral guidance and the concept  of  placing  conventional
traveling screens at an angle to the flow.


Revolving Drum Screens - Vertical Axis

At least two types of vertical axis revolving drum screens are in use in
U.  s.  water  intakes,  but not in facilities connected with industrial
cooling water systems.

    a.  The vertical drum revolving in an opening in front of the  pumps
    as shown schematically in Figure 111-31.

    b.   The  vertical drum revolving around the pump itself as shown in
    Figure 111-32.

The screen mesh is placed on a vertically revolving drum.    Water  level
variations  can  be  handled  without  difficulty.   A vertical jet spray
system can be mounted inside the drum to wash off debris.    However,   no
convenient  way  has  been  developed  to  move the debris away from the
screen face area.

Figure III-31 shows the drums lined up in such a manner that  a  passing
river  flow  will carry away debris and would also carry fish to safety.
Obviously the reliable performance of  this  system  will   depend  on  a
                                 74

-------
                      TRASH  BARS

                            i:ci
             CONTINUOUS
             ROTATION
          O
o
                                  SPRAY HEADER
                                  FOR TR/A5M REMOVAL
£ CIRC. WATER  PUMPS
            SCHEMATIC PLAN


ADAPTATION OF HORIZONTAL TRAVELING  SCREEN



           FIGURE IH-30
                75

-------
                RIVER  FLOW
                           -TRASH BARS
                                           "SPRAY JET PIPE
                                           FOR CLETANIA/6
             I I I I t I I 1 I II	1 M I I I I t I I I t~~1 M I M I ! I I I I |	[ I I I I I I I j I 1 1 II	1
                               PLAN
                                                 PUMPS
                  SCREENS
TRASH BARS
\HI6ti PWATER
 LOW.VATER
•••-t-f--
               o
TO PLAMT
                     SECTION  A-A
         REVOLVING DRUM SCREEN - VERTICAL AXIS
                     SCHEMATIC
                   FIGURE 111-31
                         76

-------
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strong  one  directional  passing  current,  which is a feature severely
limiting the locations where the screen  would  be  effective.   without
such  passing  flow  the  debris  would  simply  pile up in front of the
screens.  Fish would be scraped or jetted off only  to  impinge  on  the
same or adjacent screens.

Figure  111-32  shows  the  screening  element  encircling  the pump and
revolving around the pump.  One major screen manufacturer  nas  supplied
such  screens  for  relatively  small, 0.19 m3/s (3,000 gprn) , powerplant
auxiliary pumps.  Another version has been independently  developed  and
used  for an irrigation water intake by the Prior Land Company of Pasco,
Washington.  Although this  system  is  experimental  and  nas  been  in
operation  for  only  about  a  year  it has served Prior Land's special
needs.   The  system  has  had  mechanical  difficulties,  however,  and
required major overhaul during the non-irrigation season.  Moaifications
and  new designs are underway.  A vertical spray washing system has been
installed, but no satisfactory provisions have been made  to  carry  the
debris away once it has been washed from the face of the screen.

The  screen  enveloping the pump must be large in diameter compared with
the bell in order to achieve an acceptable low screen velocity.  Only  a
small  vertical  section  of the screen will be effective since the flow
lines into the pump bell traverse only a limited area of the surrounding
waterway.

The vertical drum screens described here are not sufficiently  developed
to provide protection to fish and appear to be of marginal effectiveness
in handling any but very light debris loads.


Revolving Drum Screens - Horizontal Axis

Horizontal  axis  revolving  drum screens are widely used throughout the
world.  There are many variations functioning in quite  different  ways.
In  the United States, however, they have had practically no application
and are not supplied as a  standard  design  for  the  water  quantities
required in powerplants.

A  simple  drum  installation  is  shown in Figure 111-33.  This type of
screen is placed with its longitudinal axis horizontal across the intake
channel.  The screening  media  is  located  on  the  periphery  of  the
cylinder.   The  screen  rotates  slowly  with its exposed upper surface
moving downstream just below the water surface.  Because it operates  in
this  manner  it  can  be used to separate fish from the water flow with
minimum impingement, if mesh approach velocities are low.  Debris is not
removed efficiently.

The important design parameters for the drum screen are mesh size,  drum
diameter,  drum  rotation  velocity,  and velocities through the screen.
The velocities  through  the  screen  are  difficult  to  control  since
                                  78

-------
            4
                          Flow/  jo PUMP -£>TB:UC"JV
r-FISH AMD Deb£lS

I  COLLECT I OM
            C
                      il

                      • L
        plow ouf
       i
I
U     I
                           F to
I
                                    FI5M AUO
                               fr.•• •»•-•> ^'- •.  .•»,f'  -v -
                                        —
                                          A-A
           REVOLVING DRUM SCREEN HORIZONTAL AXIS



                        FIGURE 111-33
                          •SCE.S-B-U
                               79

-------
portions  of  the  screen  are  alternately  moving with and against the
intake flow.  The horizontal drum screen as shown is also  sensitive  to
water level changes.

Drum  screens  may  be  designed as impinging or non-impinging depending
upon the size of the fish to be separated and the velocity of the screen
and the rate of flow in  the  channel.   The  impinging  design  is  not
preferable  because  of possible damage to the fish while on the screen.
It is also difficult to remove the fish subsequent to impingement.  High
pressure sprays have been used but these can also damage fish.

No drum screen was found to  exist  at  a  U.  S.  powerplant.   Several
horizontal  drum  screens  have been used to divert fish from irrigation
canals.  A major installation of this type is the fish bypass  structure
of  the  Tehama-Colusa  Irrigation Canal operated by the U. S. Bureau of
Reclamation, shown on Figure 111-34, taken from Reference 21.  Since the
water is used for irrigation, debris removal is not as important as at a
powerplant or other industrial intake.  Note that  the  drum  screen  is
placed  at  an  angle  to  guide  fish to a downstream bypass similar to
horizontal screens and louver diverters.  A supplementary pumping system
would be needed to produce the desired bypass flow.   There  is  also  a
problem  in  obtaining  good  seals  at  the bottom and against the side
walls.

The advantages of the illustrated  drum  screen  over  the  conventional
traveling water screens include the decreased number of moving parts and
the  possibility of utilizing more than half of the total screen mesh as
effective screen area.  However, an industrial intake  designed  on  the
pattern  of  Figure  III-3U  would  cost considerably more than the con-
ventional intake.

In European practice the term "drum screen" covers a much broader  range
of  designs.  For the purposes of this brief review the terms "drum" and
"cup" are generally interchangeable, depending  on  each  manufacturer's
specific  definition.   Many  of  these  are  used  extensively in major
powerplant intakes and are highly regarded for  their  effectiveness  in
water  cleaning  and  their  serviceability.   None  has  been designed,
however,  with  the  welfare  of  fish  in  mind.   A  few   appropriate
modifications  have  been  made  to  lessen environmental impact, but in
general this facet of water screening has not been given much attention.
The following types are readily available and often used:

    a.  Figure III-35, single entry cup screen, where the  water  enters
    at  the  end  (side)  of a large rotating drum and passes our through
    screen mesh on the periphery.  It is limited in size to  about  9  m
    (30')  in  diameter  because  of  the cantilever nature of the shaft
    support.

    b.  Figures 111-36 and 111-37, double entry cup  screen,  where  the
    water enters the rotating drum from both ends  (sides) and passes out
                                  80

-------
(XI
                                         FISH  BYPASS STRUCTURE




                                           FIGURE 111-34

-------
                          DEBRIS REMOVAL SYSTEM
ROTATION
              MAXIMUM WATER LEVEL! \1
                     ^\
         \\\ MINIMUM WATER LEVEL
              SECTION ON A-A
              SCREENED WATER
                   ,-t-,
             DIRECTION OF FLOW
             UNSCREENED WATER
       SINGLE ENTRY CUP SCREEN
             figure ITI-35
                  82

-------
                       DEBRIS REMOVAL SYSTEM
ROTATION!
 SCREENED
  WATER
 SCREENED
  WATER
          DOUBLE ENTRY CUP SCREEN
                 Figure 111-36
                    83

-------
DOUBLE ENTRY CUP
    SCREEN
                                                                 OUTLET
                                                                SCREENED
                                                                 WATER
                   SCREEN STRUCTURE WITH
                  DOUBLE ENTRY CUP SCREENS
                       Figure 111-37
                             84

-------
  through  the mesh on the  periphery.   These  screens  have been made as
  large as 18.3 m (60')   in  diameter.    Efforts   have  been  made  to
  provide oversize debris lifting buckets to  carry fish in water up to
  the debris removal system and trough  at the top of  the drum travel.

  c.    Figure 111-38,  a double entry drum screen  where the screen mesh
  covers the ends (sides) of the drum and  the periphery  is  closed.
  Water  enters  the  sides  and  also   leaves one side through a pipe
  around which the drum rotates. This screen  rests on piers without  a
  surrounding  concrete structure, a mounting which permits water flow
  around all sides and which thus provides escape routes for fish.  In
  this respect the setting is similar to  the  double  entry  vertical
  traveling  screen  offered  by  a  U.  S.   manufacturer and shown in
  Figure 111-25.  Screens of this type  cannot be   cleaned  efficiently
  because  of  the  tendency  for the debris  to fall back into the raw
  water as the screen rises.

The structure required to mount drum or  cup   screens  is  substantially
larger  and  more  costly  than  the vertical traveling screen structure
designed to handle the same quantity of water under the same conditions.
They are reputed to be easier  to  maintain   (the  horizontal  shaft  is
located  above normal water level), there are fewer mechanical parts and
there is no possibility of carryover of  debris   into  the  circulating
water system.


Rotating Disc Screen

Figure  111-39  shows  a  typical  rotating disc screen, a type which is
suitable  only  for  relatively  small   flows  and  small  water   level
variations.   The  screen mesh covers a flat disc set at right angles to
the water channel.  The disc rotates around a horizontal axis,  bringing
the  dirty  screen  face above water where high pressure sprays wash the
debris into a trough similar to that  used  for  conventional  traveling
screens.   It  has  a  minimum  number  of  moving  parts  and  is  thus
inexpensive to buy  and  maintain.   The  circular  screen  shape  makes
inefficient  use  of  available  area of the  incoming water channel.  No
more than about 35% of the total screen face  is being used  at  any  one
time.

Such  a   screen has no advantage over other common screens from the fish
protection point of view.  It also has most of the drawbacks,  including
probability  of  fish  impingement, the need  for high pressure sprays to
remove fish and debris and the  need for a very large  screen structure to
limit screen approach velocities to those now being considered for  fish
survival.
                             85

-------
           5ECTIOU A-A
DOUBLE ENTRY DRUM SCREEN OPEN WATER SETTING
             FIGURE III-38
                   86

-------
                                                                     Rotation
Access platform
if required   "-
                                   Electric drive
                                   unit
                                                     Screening panels
                               ROTATING DISK SCREEN
                                  BASIC ELEMENTS
                              ROTATING DISK SCREEN
                                  IN OPERATION


                                  Figure 111-39
                                       87

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Miscellaneous Mechanical Screens

Water   treatment   plants,   sewage  disposal  facilities  and  various
industries requiring service water employ many other  configurations  of
mecharical  screens,  strainers and filters.  Many are designed for much
smaller water flows than are required fcr powerplant  circulating  water
systems.   TVS  with  most  of the screens described in this section they
were designed specifically to produce screened  water,  nor  to  protect
fish.   consequently,  they  do  not  have  features  we  feel are worth
considering for incorporating into facilities being designed  with  fish
protection as a major criterion.
In  addition  to  the  screening  device,  other  types  of  systems can
influence the design of intake structures.  The  need  for  fish  bypass
systems  ir.  conjunction  with  some  of  the screening systems nas been
discussed in previous sections.  Fish handling and bypass equipment  can
also  be  used to return impinged fish back to the waterway.  Relatively
little  work  has  been  done  on  developing   these   facilities   for
incorporation  into existing industrial intakes.  Most of tnese types of
facilities have been installed at irrigation diversions operated by  the
U.  S.  Bureau of Reclamation and the State of California.  A great deal
of work has been done in  the  Pacific  Northwest  in  diverting  salmon
around  hydroelectric impoundments.  As more powerplant intake designers
become aware of the need for fish handling and bypass  facilities,  they
will have a greater impact on the intake  configuration employed.

Fish bypass and handling facilities of interest include the following:

       fish pumps

       fish elevators

       "crowding devices"

       bypass  conduit

       modifications  to vertical traveling  screens

 Fish  Pumps

 Fish   pumps have been used  for  many  years.   The  rotary  type of  pump with
 open  or  bladeless  impellers  seem to  cause the  least  amount of  damage  to
 fish.    However,   all rotary   pumps   are  not  necessarily  suitable for
 pumping  all types  of  fish..   The use  of hydraulic   eductor   pumps  was
 thought   to   be   ideal  for  fish pumping.  However,  fish  passing through
 such  eductors encounter  high pressures which seem to cause more  damage
 than  mechanical  pumps 13.
                                  88

-------
 Fish  Elevators  and  "Crowding  Devices"

 Several  types  of bucket  elevators have  been  tested  in elevating fish on
 a  batch  rather  than a  continuous  basis.   One  such system was  tested  at
 the   Tracey   Pumping Station  by the National  Marine  Pisneries Service in
 conjunction with the horizontal traveling screen.  This system is  shown
 in Figure III-40.   The fish are first  concentrated over the  lower bucket
 by use  of   a  crowding  device and then raised  and  dumped into -trie fish
 trough for bypass.   This  type of  system  might be quite useful at intakes
 where fish might congregate in quiescent zones created by such things as
 curtain  walls and other intrusions into  the screen channel.


 Fish  Bypass and Transport Facilities

 After being concentrated  and  removed from the  screen  well,   tne  fish
 require  a  means   of   conveyance  back   to a hospitable environment the
 waterway.  The  design  of  the  bypass system should  minimize the time that
 the fish is out of  water   and insure  safe   and  rapid  return  to  the
 waterway at  a location  sufficiently  removed from the intake to prevent
 the recirculation of fish and reimpingement.   Once the  fxsh  have  been
 raised to an  elevation above  that of the waterway  they can be discharged
 to a trough   or pipe for gravity return to  the waterway.   Care must be
 taken in the design of the fittings and  elbows of  the  discharge  conduit
 to prevent  undue   stress on the fish.   Furthermore, discharge of fish
 should be made  to a hospitable environment..   Considerable experience in
 designing and   operating   long fish  bypasses  for  both upstream  and
 downstream  migrant salmon   has  been  obtained in  the  Pacific Northwest.
 The technology  exists  for these types  of systems.  Where conditions  do
 not   permit direct  hydraulic  conveyance,  fish can  be trucked back to the
 waterway.  Trucking fish  over Icng distances   does not  seem   to  cause
 unacceptable  mortalities.  Both  trucking and airlift  nave been used for
 seeding  waterways with fish.   Reference  13 has some  suggested  criteria
 for trucking fish.

 Modification To Existing  Traveling Water  Screens

 The   fish bypass facilities described  above were intended to remove fish
 from  the  intake  structure   to   prevent   impingement.    An   interesting
 example  of  modifying  an existing  traveling  water  screen to bypass
 impinged fish is described below.

 The installation is  a  major nuclear  station   on   the   eastern  seaboard
 (plant  no.   5111).     The  station   is   located  above  the river  and 2.7
 kilometers (1.7 miles)   from the intake.   Water is  pumped  from  the   river
 into  the  "high  level"   canal   from  which   it flows  by gravity  to the
 screens located at the plant.   Apparently  juvenile fish  pass through the
 pumps and become entrapped in the  canal  for   subsequent   impingement on
 the   screens.    The  first  modification  made was to  connect  the  screen
waste flow to the plant discharge  canal using a 45 cm  (18")   polyethylene
                                89

-------
                                      FISH TROUGH
g-i m
                                               2-1 W DEEP
     :SCREEN WASH BAR - SINGLE BAR
         FISH BASKET COLLECTION SYSTEM




               FIGURE DII-40
                     90

-------
pipe.  Tests made on the system in  this  condition,  showed  that  this
transport  system  minimized  mortality  when  the screens were operated
continuously during the cold water period  but  that  damage  was  above
acceptable  levels during the summer.  Mortality was primarily caused by
high screen wash water pressure and by recycling of  fish  at  the  air-
water  interface of the screen front.  It was concluded that "recycling"
was a higher mortality factor in the summer than in the  winter  because
tha  more  active  fish  would flip back into the water after the screen
basket cleared the water surface  and  be  reimpinged.    Tnis  would  be
repeated until the fish were dead or weak enough to remain on the narrow
lip until the basket reached the wastewater stream.

The  modifications  are  shown  schematically  in  Figure  111-41.  They
consisted of bolting  a  10  gauge  steel  trough  on  the  lip  of  the
conventional  screen baskets.  The troughs were positioned to maintain a
minimum of 5 cm  (2")  of water depth during the time  of  travel  between
the  water  surface  and  the  head shaft sprocket.  The new screens are
designed to be continuously operated, thus  reducing  the  time  of  any
possible impingement of fish on the screen to two minutes or less.

The  screen  wash  system was also modified to minimize damage caused by
the standard high pressure jets.  As the screen travels  over  the  head
shaft  sprocket,  the  fish will be spilled onto the screen surface.  On
further rotation, fish will slide down the screen and be deposited  into
a  trough of running water for transport back to the river away from the
intake  structure.   A  low  pressure  screen  wash  system   has   been
incorporated  into  the  design  to  aid  in  removing   crustacians  and
returning them to the river.

Since these modifications are only now being installed  at the plant,  no
data  on the performance of these modifications are available.  No prior
model testing was performed and a prototype will be used to  verify  the
capabilities  of  the  system.   If reasonable efficiencies in bypassing
fish safely are obtained, this type  of  system  might   be  utilized  to
modify  other  intakes where impingement is a problem.   The system could
be installed on most existing conventional  intakes,  and  the  cost  is
roughly  30% of the intial screen cost plus the cost of the bypass line.
The intake is not substantially changed.

One disadvantage of this system may be a lack of acceptance on the  part
of  some  of  the  regulating  agencies.   We  noted a  problem regarding
discharge of debris after it has been removed from the  waterway.   As can
be seen from the figure, there is no way to avoid discharging a  portion
of  the  debris  in the fish bypass channel.  Stringent resrrictions may
prevent the use of this system at many locations.
                                  91

-------
                    LOW  PRFSSURE  JETS


                    FOR
/O DISCHARGED 	 1
QUQHS — • — <* i
•*• r
c
i
t
S1 ^

^\
j
d 	 	 	 ijiru pRrsc.(yRF JFT
3 FOR RFftPK RFN|/
. 	 	 , _*' ^ n CT i M c i r~ p1 T" r\ \ i T~
LDUNMo UL.' i (JU I
1 WHICH HAS OTHER
, ex DOWNSTREAM)
3 ><="* 1-LOW

^--U> V~ FI5M
"5
DUAL
AT SURREY,
SCREE/MS

FALL OFF1
          SECTION
        SCREEN  FACE
  ^*.-—     -—

\ fA POOR  FEATURE)


 \
             FRONT OF 0A5KET
             KIGW TO KEEP
             FISH  IAI
               IO-5*
                                      :FISH RENOVAL
                                          DETAIL
BASKET  DETAIL
      MODIFIED VERTICAL TRAVELING SCREEN


            FIGURE 111-41
                   92

-------
Intake Structure Designg

In addition to special biological considerations, the size and shape  of
an  intake  structure  should  be  determined  to  a large extent by the
following factors:

    The quantity of intake flow

    The type of screening  system  used  and  allowable  water  approach
    velocity

    The relationship of the intake to the water source

    Miscellaneous  factors  such as need for storm protection, avoidance
    of excess sedimentation, ice control

Since most existing powerplant intakes employ the conventional traveling
water screen  they  will  be  referred  to  as  "conventional"  intakes,
implying that they are equipped with such a screen.


Conventional Intakes

There are three general classification of conventional intake structures
based  on the relationship of the intake to the water source.  These are
as follows:

    Shoreline intake

    Offshore intake

    Approach channel intake

Shoreline Intake

The most common intake arrangement is the combination of  inlet,  screen
well and pump well in a single structure on the edge O£ a river or lake.
The   best  designation  for  this  installation  is  "pump  and  screen
structure", to clearly distinguish it from  individual  structures  also
commonly used.  A plan view of this type of structure is shown in Figure
111-42.   A  cross section of the shoreline structure is shown in Figure
III-U3.  Note that the water passes (in order)  the trash rack, the  stop
log guide and the traveling water screens on its way to the pumps.  This
type  of  structure  is  used  where  the  slope  of  the  river bank is
relatively steep and there is relatively little movement  of  the  water
edge  between  high  and  low water.  A variation of shoreline structure
design is shown in Figure 111-44.  Here a skimmer wall is used to insure
drawing in of cooler lower strata waters.  Curtain walls, used primarily
to protect trash racks and screen from logs and ice, can also be used to
draw in cooler water.
                                   93

-------
            4-
5HORELINE7
                 i
  LAKE
 OR RIVER
                        PUMPS

                         j-PIPELINE
.WATER SCREENING
   FACILITY
              PLAN
     SHORELINE PUMP AND SCREEN STRUCTURE

             FIGURE 111-42
                 94

-------
Mech Trash
Rake
Screen _»
Wash Pump
             CONVENTIONAL PUMP AND SCREEN STRUCTURE
                        FIGURE 111-43
                               95

-------
                ROTATING SCREEN-/

            TRASH BAP5-
  ,  WATER
PUMP

TO PL4NT
          H.W
          L.W
SKIMMER WALL.-*-
     LOW LEVEL
      INTAKE
         7/>/X '^T
 PUMP AND SCREEN STRUCTURE WITH SKIMMER WALL

                FIGURE 111-44
                    96

-------
Offshore Intake

The offshore design separates the inlet from the pump well.   This  type
of  intake  is used where there is a significant lateral movement in the
waterway between  high  and  low  water  where  there  is  a  particular
technical  or  environmental  reason for utilizing the water supply at a
distance from shore.  Figure 111-45 and 111-46 show two similar concepts
of such an intake.  The design shown in Figure III-46 employs a  siphon.
The  term siphon here refers to a gravity pipe placed above the level of
the water  and  thus  flowing  under  vacuum.   The  prevision  of  fine
screening  facilities at the ccnduit inlet offshore is often impractical
because  of  construction  difficulties,  because  of  the  navigational
hazards it presents or because of difficulty of access for operation and
maintenance.  Therefore, the fine screens are usually located in a shore
structure  as  shown  in both Figure 111-45 and 111-46.  Flow velocities
are commonly rather high (say 1.5 to 3.0 mps) in the inlet  pipeline  to
reduce  its  cost  and  most species of fish would not be able to escape
entrapment in the system after entering it.   Therefore  a  considerable
amount  of interest centers on the inlet structure as the place to guard
against fish entrapment in an offshore intake.  Since  offshore  intakes
can  have  screens onshore, diversion weirs or crowders can be used as a
second line of control to remove fish prior to possible interaction with
the screen.


Approach Channel Intake

In this type of intake, water is diverted from the main  stream  into  a
canal  at the end of which is the screening device.  Tnis type of intake
is shown in Figure 111-47.  Channel intakes  have  often  been  used  to
separate  the  plant intake and outfall for the control of recirculation
effects, to permit location of the pump  structure  where  it  can  more
easily  be  constructed  or  to  reduce total system friction losses and
costs by replacing high friction, high cost pipe with lew friction,  low
cost  canals.   It  may  also  be  used  to  remove the intake  from the
shoreline for aesthetic reasons which  are  discussed  elsewhere.   Fish
will tend to congregate in these approach channels and tnus increase the
incidence  of entrapment at the screens.  A modification of the approach
channel concept is shown in Figure 111-48, where  the  screen  structure
has been placed at the entrance to the channel and becomes essentially a
shoreline  intake,  without  the fish entrapment hazards inherent in the
channel scheme.  However, care must be taken with the  shoreline  intake
to avoid velocities which could increase impingment.


Conventional Intake Design Consi derations

In  addition  to  special  biological  considerations,  other  important
considerations in the design of conventional pump and screen  structures
are the following:
                                   97

-------
         ROTATING  SCREEN-
    TRASH  BARS   -
V1EAD LOSS IN
 INLET PIPE    	
                     TO]
                                                    CIRC. WA7TR
                                                          PL/MP
                                                    V
  FISH CAP
(VELOCITY CAP)
                                                           TO PLANT
           PUMP AND SCREEN STRUCTURE WITH OFFSHORE  INLET

                        FIGURE 111-45
                            98

-------
vc
vc
          SIPHON  INTAKE
      RIVER OR

      '.. LAKE-
                       i
PRIMING

CONNECTION
                                                                 SCREEN
                                                                    *


                                                                  V
                                                                              -PUMP
                                 PROFILE THROUGH WATER  INTAKE




                                          SIPHON TYPE




                                       FIGURE  111-46

-------
OUTFALL
           GENERATING
             PLANT
        LAKE
         APPROACH CHANNEL INTAKE—^
             APPROACH CHANNEL INTAKE
                 FIGURE 111-47
                      100

-------
Lake



 or



Rivet
r
        Water Screen Facility

              (Example 2)
 ^	P-4
                   "^"Channel
O-


 OM
 M



O
                               Pump Well
   SCREEN LOCATION - CHANNEL INTAKE




           FIGURE IH-48
                    101

-------
    water level variations

    Inlet design

    Screen placement

    Screen to pump relationships

    Flow lines to the pump and the pump chamber configuration

    ice control provisions

    Access to the structure for operation and maintenance

Inlet  safety  design  considerations  will be different for each of the
three  classifications  of  conventional  intake  structures.   For  the
shoreline  intake  an  important  consideration  is to avoid significant
protrusions into the waterway.  This is shown diagramatically in  Figure
111-49.   The  top  sketch shows an example of undesirable intake design
where the side walls of the intake structure protrude into the  waterway
and create eddy currents on the downstream side of the intake.  Fish are
sometimes  found  concentrated  in  these  areas,  a situation which may
increase the possibility that they will become entrapped in the  intake.
The  bottom  sketch  shows a more suitable design with no portion of the
intake structure protruding into the flow.  Of course, this would not be
significant at structures drawing water from a lake shore location where
cross flow velocities are negligible.

Screen Placement

Most conventional intakes are designed with the traveling water  screens
set  back  away  from  the face of the intake between confining concrete
walls.  As shown in the top sketch of 111-50, this  creates  a  zone  of
fish  entrapment  between  the  screen  face and the structure entrance.
Small fish will not swim back out of this area.  The  bottom  sketch  of
the  same  figure  shows  an  alternative  screen placement with screens
mounted flush with their supporting walls.  The trash rack  facility  is
so  designed  that  there is an open passage to the waterway directly to
both left and right of the screen face.  In this  design,  there  is  no
confining  screen  channel  in  which  the  fish  can  become entrapped.
Figures 111-51 and 111-52 show two recent  designs  of  "flush"  mounted
screen structures.  The first is the screen and pump for a major fossil-
fueled  plant  in  the Northeast  (plant no. 3601) .  Figure 111-52 is the
pump and screen structure for a major fossil-fueled plant  on  the  west
coast   (plant  no.  0610).  Note that the screens are mounted flush with
the shoreline in each case and that fish  passageways  are  provided  in
front  of  the screens.  In these designs there is no provision for stop
logs to permit  dewatering  the  screen  wells.   Extending  the  screen
support  walls  to  provide  stop  log  guides  would defeat the "flush"
mounting principle.
                                   102

-------
             RIVFR  FLOW
                     SCREENS
SHORE LINE-
-> -h-i+) --
                                  PROTRUDf/NG
                                  - WALL
        -AREA OF WATER EDDIES
                                PUMPS
               POOR DESIGN
           RIVER FLOW
  SHORE UNE-
                              PUMPS
              GOOD DESIGN
           SHORELINE INTAKE  STRUCTURE
                 FIGURE IH-49
                    103

-------
                Bars
Screen lVe//s
  (ilsh ehtrapmen't areas)
Sharel/ne.
i 1 1 1 j 1 1 ni 1 1 1
x
X


x
1 1 1 1 ! V 1 1 \

Scrzer

                                TTTTTLI~Xin I I I I INITTTI~
                  CONVENTIONAL
                                                       Pumps
    Trash Bars
                  MODIF/ED ScKEEN
                    (FLUSH MOUNTED
                         FIGURE  111-50

                            104
                                                             Screen
                                                        umps

-------
o
Ul
      Trove lino

      Trash Rake
                                 Travel/no
                                                                                               lo  ower P/chi

                                                                                               !2 It ID. Ccnc
                            \
                                       IP
                                        (I"
                                     %
                                         PUMP  AND SCREEN  STRUCTURE



                                               FIGURE  ni-51

-------
                      •BAY-
UMUliiililJ ;J!UliL^a;iLiiiliiUJJi]lUi I ti
tH     <-'     U    U     u
                                L )
SCREENS FDR
UNITS 5 i 6
NOT SHOWN
                  ,-_/-,_/-,.__
;®
                              /'
                                                              •TRASH RACKS


                                                              TRAVELING SCf-:

                                                                WV/GMALL
n
                                           ©t-
                                                 ££/••//, TERING
                                                 5': OP LOG
                                                 LOCATION
                    	\^p!JMps T0 UNIT5 i ro 4
           SECTION- PLAN
    MHWL+3.Z
                             TRAVELING SCREEN

                                          PUMP
           SECTION- ELEI/ATION


               PUMP AND  SCREEN STRUCTURE

                    FIGURE  111-52
                        106

-------
Where channel sections leading to the screens cannot be avoided  due  to
some unusual condition, proper design of the screen supporting piers can
reduce   the  fish  entrapment  potential  of  the  area.   This  design
consideration is shown in Figure III-53.  In Figure III-53A  an  example
of  incorrect  pier  design is shown.  The pier which protrudes into the
flow presents a barrier to fish movement.  They cannot  make  the  turns
required  to  escape  the  screen.   Figure  III-53B  shows  a much more
suitable design.  With the extended portion of the pier eliminated,  the
fish  can  move sideways and rest in the relatively still water near the
face of the pier.


Maintaining Uniform Velocities Across the Screens

It is essential  in  good  screen  structure  design  for  environmental
protection to maintain uniform velocities across the entire screen face.
When  flow  is  not  uniform  across  the screen, the potential for fish
impingement is increased.

Figure 111-54 tabulates a typical run of a model test series made for  a
major  plant  in  the  northeast   (plant  no.  3601).   The variation in
velocities is evident.  Flow distribution in many  existing  intakes  is
much less uniform than indicated in Figure 111-54.

There  are  several  ways  in which a non-uniform screen velocity can be
created.  Figure III-55 illustrates some of  the  factors  which  create
non-uniform  velocities  in  the screen area.  Sketch A of Figure 111-55
shows the condition when water approaches the  screen  structure  at  an
angle.   Flow  tends  to concentrate at the downstream side of the water
passage entrance and in some  cases  may  even  flow  backwards  on  the
upstream  side.   Sketch B shows the effects of curtain walls projecting
into the water passage.  Curtain walls  similar to that  shown  here  are
frequently used to reduce the intake of surface debris or to confine the
entering water to a lower and normally  cooler strata.  The result is not
only the creation of non-uniform velocity conditions at the screens, but
also  the creation of a dead area where fish may become entrapped.  They
will not usually swim back to safety under the wall.  Sketches C  and  D
show  the  effects of pumps or downstream water passages so located that
water is drawn  from a limited horizontal or vertical strata as it passes
through the screens.  Pumps or gravity  exit pipes may be  too  close  to
the screen or may be offset from the screen center.  Hydraulic Institute
standards  recommend  a  minimum  distance" from screen to pump, but this
distance is established for suitable  pump  performance,  not  for  best
utilization of  the screen area.

The  obvious result of the poor distribution of flow through the screens
is the creation of local areas of  flow  velocities much higher  than  the
calculated  average  design  velocities.   Entrapment  of  fish  is thus
increased.
                                 107

-------
                      SCREE&L
                         I
                   IUNDESIRABLE
 FISH  CANNOT -
MAKE TURN IN
THIS AREA
               FIGURE A


        UNSATISFACTORY DESIGN
If
SCREES'

X 
                               _4-
t
 RSH
JN TH
                    REST
                    5 AREA
\
               FIGURE B


             IMPROVED DESIGN
       PIER DESIGN CONSIDERATIONS


           FIGURE 111-53
                 108

-------
             Velocity meosurements ( In ft/sec ) at entrance
             of pump Bay No. 3 for the following conditions!


             Pumps 1, 2 and 3 In operation; 2 ft/sec river
             flow with the water level of 0' , and full wall

             openings.
First cross-section ( upstream from the frash-rolce )

                 (a)     (b)       (c)      (d)     (e)      (0


NearBottom      0.34J  1 .06 \    1.12?   0.74\  0.95 1   0.75 f

                0.45!  0.93 t    1.02\   0.89 \  0.75 \   0.83/


                0.57\  0.67 t    0.33 f   0. 41 /  0.31 f   (nil)
Mid-Depth

Near Surface
Second cross-section ( In the flshway )

                 (a)    (b)       (c)      (d)     (e)      (0


NearBottcxr,     0.39*  0.57\    0.99t   (nil)    0.75t   0.73 1


Mid-Depth       (nil)   0.57 1    0.95 1   (nil)    0.90 1   0.80 t

Near Surface     0.62t  0.68 /  0.87—0.77*0.95-0.72-



Third cross-section ( downstream from the screen)

                 (a)    (b)       (c)       (d)     (e)      (0


Near Bottom     0.68t  0.84 f    0.80 t  0.60t  0.74 t  0.67 t


Mid-Depth       O.BOt  0.95 t    1.06t  0.67to.8ot  0.81  t


 Near Surface     1 .20t  l.Olt    0.47 t  0.63 1 0.63 t  (nil)  t
            CIRC  WATER
               PUMP
'•• °o" 1"*" *
)
TRAY
SCREEN
 "yf"
                                           HN _
                                                LU
                                                         Ul
BAY *3
B E

°"-^ •* .. *
                                            O -
                                                tn
      SCREEN  AREA  VELOCITY  DISTRIBUTION

                   FIGURE  111-54
                         109

-------
             e-
                               FISH ENTRAPMENT

                                   AREA-7
                 PUMPS
      GRAVITY  PIPE

    TO PUMPS AT PLANT
                             LJ
                             UJ
                             cn
1 H ^

 i Lu =c
  LL C-£
  Lu ui
                                     UJ
                                             •TO
FACTORS CONTRIBUTING TO POOR FLOW DISTRIBUTION



             FIGURE  III-55
                  110

-------
One basic consideration in  initial  layout  of  the  structure  is  the
matching  of  the  pumps to the screens.  Figure 111-56 illustrates four
intake variations to accommodate pumps of a wide range of sizes.  Sketch
A is an intake for several small pumps served by one screen.  The  shape
is  produced  by the fact that the flew required by the pump is so small
that only a minimum sized screen is required.  Sketch B is a one pump  -
one  screen arrangement common for medium size pumps up to about 100,000
gpm.  Beyond this pump size the physical limitations on the screen  size
 (14 foot  trays  or  baskets  are  the  maximum  commercially available)
requires the use of  multiple  screens  per  pump.   Sketches  C  and  D
illustrate  possible  combinations.   Care  must  be taken to locate the
screen with respect to the pump in a manner which will properly  utilize
the  entire  screen  surface.  If a very low screen velocity is required
for a very large pump installation, the length of structure required for
the screens may  be  greater  than  that  which  will  be  hydraulically
suitable  for  the  pumps.   Such  a  requirement  could  result  in the
configuration shown on Figure 111-57.

Pump Runout and the Effect on Screen Settings

Sketch A of Figure III-58  shows a typical one  screen   per  pump  intake.
If  the  screen  is  sized   for  the design  flow  of the pump, the screen
velocities will substantially increase  during  periods  when only one pump
is  in operation.  This is the result of the  "runout" characteristics  of
the  pump  which  tends  to  pump more water  as the total system flow and
head losses decrease.  As much as  40% flow increase might  be   expected.
Operation  in  this  manner  is common  in those areas  where winter water
temperatures are much lower  than  summer  temperatures.   We   may  then
expect  an  increase  in screen velocity during those  cold water periods
when  lethargic  fish  might be   least able  to  resist   the   flow.
consequently,  if  this  type  of  setting   is used, the screens must be
designed for the expected  runout flow of the pump.

An  alternative to the individual bay setting shown in  Sketch   A  is  to
place the pumps as shown in  Sketch B of Figure III-57.  In this case, an
open  chamber  is  located   in  the  side wall between the pumps and the
 screens.  The operating pump may thus utilize  a part of the screen  area
normally  used  for  an  adjacent  pump.  Field and laboratory tests show
that only a small part of  the adjacent  screens are effectively  utilized
 in  this  situation,  but  that  a   small  part   will  be   sufficient to
 compensate  for the increase  in pump  flow if  the   screens   and   pump  are
 properly located.

 An  intake  of  the  latter  type will be larger and more costly than the
 former.  Maintenance procedures may  be  complicated by  the  fact  that  the
 central  bay  cannot  be dewatered and  also  the dewatering  of individual
 screen  and  pump bays becomes more  complex.
                                  Ill

-------
 Screen
                      Pumps
                                       Screens
                                                            umps
Screens
            B
                 o
                 o
                 o
Pumps
                                                  D
                                     Screens
                                                             PUIT
                 PUMP/SCREEN RELATIONSHIPS
                      FIGURE 111-56
                      112

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             SHORE" LINE
                                         PUMPS
PUMP AND SCREEN STRUCTURE FOR LOW INTAKE VELOCITIES




                 FIGURE 111-57






                     113

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     A
    B
EFFECT OF PUMP RUNOUT




  FIGURE m-58
       114

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Design of Ice Control Facilities


Most powerplant intakes located in the northern latitudes must have some
provision for ice control during  the  winter  months.   Sheet  ice  and
"frazil"  ice ("needle" ice) can cause flow blockage at the intake.  The
system  most  frequently  used  to  control  the  ice  problem  is   the
recirculation  of  a  portion  of the v;armed condenser water back to the
intake.  Figure III-59 shows a cross section of a powerplant intake with
the ice control header and discharge ports  located  upstream  from  the
screens.   A  variation  of  this  method  would  be to recirculate only
intermittetly to minimize fish retention at the intake area.  The sketch
shown is for a major nuclear plant located on the Mississippi (plant no.
3113).  Other ice control systems that have been tried  have  been  less
successful.    In  particular,  several  attempts  to  use  an air bubble
curtain  (similar  to  that  described  in  the  section  on  behavioral
screening)   to  control  ice  have not been completely effective.  Other
methods of ice control are to place the  intake  well  below  the  water
surface, or, for sheet ice, to agitate the water surface with propellers
or  similar  devices.   The  problem  with  the use of the recirculation
system for ice control is that it has been shown that  fish  concentrate
in  warmer  water  in  the  winter  time, thus increasing their possible
interaction with the screen.  It has  also  been  shown  that  fish  are
lethargic  in  the  cold  water periods and cannot swim well against the
intake flow.  These two factors can combine to make the traditional warm
water recirculation system less than  desirable  from  an  environmental
standpoint.

It  is  suggested"  that  traditional warm water recirculation systems be
avoided.  While the feasibility of other ice control systems is  yet  to
be  proven  at major powerplant intakes, there does not appear to be any
technical limitations  to  the  development  of  alternate  ice  control
systems.


Non-Conventional Intakes

Non-conventional  intakes vary considerably from conventional intakes in
that they will use methods for separation of water and debris other than
the screening devices and/or screen mountings previously mentioned.  The
non-conventional intakes to be described in  this  section  include  the
following:

       Open setting screen

       Filter type intake

       Perforated pipe intake

       Radial well intake
                                  115

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SLUICE  GATE
 OPERATOR
                                               MAX. H.W
                                TRASH
                     RAVELING    RACK
                      SCREEN-
                                                L.W FROM PLANT
                                              "DISCHARGE*  SYSTEM

                                                  -ICE     ^
                                                   CONTROL
                                                  TUNNEL
                                                     L.L.W
                                          SLUICE GATE (FOR
                                          V/ARN
                                          RLCIRCULATION
                       .-  LADDERS

                       STOP LOG" GUIDES —

PUMP  AND SCREEN STRUCTURE WITH ICE CONTROL FEATURE

                FIGURE ni-59

-------
Open Setting Screens

Figures  111-25  and  111-38 shew two screens which have been mounted on
platforms and connected directly with the pumps which they  serve.   One
is  the  double  entry, single exit vertical traveling screen, the other
the double  entry  drum  screen  of  European  design.   Both  of  these
screening   systems   have  open  water  completely  around  them,  thus
eliminating fish entrapment areas.  A second advantage of rhese systems,
and  the  original  purpose  for  which  they  were  developed,  is  the
elimination  of  costly  concrete screen wells.  Most such installations
would require some type of trash rack protection which is not  shown  on
the figures.

Flow distribution through the screen faces may not, however, be suitably
uniform.   The  areas  nearest  the inlet to the pumps will tend to have
higher flows and velocities and may therefore result in undesirable fish
impingement.  This objection might be overcome  with  internal  dividers
and  increased  screen  sizes,  but  no  information  is  available that
indicates that such measures have been utilized.

A similar system is  being  used  at  plant  no.  1229  located  on  the
southeast coast.  The system has performed reliably for several years.


Filter Type Intake

Many  types  of  filter  intakes  have been developed on an experimental
basis  and  some  have  been  installed  in   relatively   small   scale
applications  for  powerplants.   The  essential  feature  of  all these
schemes is the elimination of mechanical screens.  The  water  is  drawn
through  a  filter  medium  such  as  sand and stone.  Such an intake is
capable of being designed for extremely low inlet velocities and can  be
effective  in  eliminating  damage  even  to small fish.  Planktonic or-
ganisms can also be protected to some extent.

Figure 111-60 is a sketch of a stone filter in use since  late  1971  to
screen  makeup  water for a large powerplant in the northeast  (plant no.
4222).  The sketch  shows  the  original  filter.   It  has  since  been
modified several times in attempts to improve its performance.  It still
has  a  tendency  to clog and cannot yet be considered reliable.  Figure
111-61 is a somewhat more complex design developed but not used for  the
makeup water of a large powerplant in the Northwest  (plant no. 5309).

A   preliminary   filter  design  has  been  developed  for  the  entire
circulating water flow to serve a  major  powerplant  in  the  Northwest
(1,500  cfs).   This  system  employs precast concrete filter modules in
seven separate filter sections,  each  capable  of  being  isolated  for
maintenance.   The entire filter complex would be about  (450 x 260 feet)
in plan.  Fairly complex  piping,  water  control  and  pump  facilities
complete the system.
                                   117

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      I MAX , y/PiPE
FFV-.
INFILTRATION BED INTAKE - PLANT NO.  4222




   FIGURE ni-60
      118

-------
Another  filter  system concept which has been used with seme success in
relatively small intakes is the "leaky dam" which consists simply  of  a
stone  and  rock  embankment surrounding the pump structure.  Water must
flow through the "dam" to reach the pumps.   The  dam  thus  acts  as  a
screen.   Very  low  water  passage  velocities  can be achieved and the
danger of fish impingement is reduced.  Very small  fish  can,  however,
pass through the openings in the stone.  A major problem for this system
in  waters  containing  suspended  matter  would be clogging.  Practical
backwashing facilities have net been developed.   An  intake  system  of
this  type has been operated at powerplant no. 5506 since late 1972.  It
has been reported be 70-75% effective in screening out fish.

Although  these  filter  intakes  would  appear  to  be  ideal  from  an
environmental point of view, they have many disadvantages.  The clogging
problem  is foremost.  In turbid waters such clogging would rule out the
filter use.  Backwashing facilities will be needed  in  even  relatively
clear  water.   The  backwashing  procedure  will  temporarily raise the
turbidity of  downstream  waters  and  thus  may  be  in  conflict  with
limitations on turbidity.  To date no large scale filter system has been
developed  and  proved reliable in operation.  The cost of such a system
will be substantially higher than for a comparable  conventional  screen
facility.


Perforated Pipe Intake

A  typical  perforated pipe intake is shown in Figure Ill-bl and 111-62.
This  concept  has  been  discussed  in  detail  under  "fixed  screens"
elsewhere  in  this report.  The figures show a preliminary design being
considered at this time for the makeup water system  of  a  major  steam
electric  powerplant in the Northwest  (plant no. 5309).  The concept can
be expanded to handle substantially greater quantities of water than the
25,000 gpm to  be  passed  through  the  illustrated  intake.   See  the
previous  discussion for a review of the advantages and disadvantages of
this scheme.


Radial Well Intake

The radial well intake is an infiltration  type  utilizing  natural  in-
place  pervious  material  as  contrasted with the artificially prepared
filter beds discussed above.  Slotted pipes are jacked horizontally into
sand and gravel  aquifers  beneath  the  river  bed.   These  pipes  are
connected  to  a  common  pump  well.   This is an intajce which has been
frequently used for obtaining highly filtered industrial  and  municipal
water.   The radial well intake is shown in Figure 111-63.  Tnis type of
intake can only be successful where  suitable  water  bearing  permeable
material  is found.  It provides a degree of screening which far exceeds
the requirements for cooling water supplies.  It has  the  advantage  of
being  the  most environmentally sound intake system because it does not
                                  119

-------
              FILTER CAPACITY 25,O


            ("3 CC-'-LS IN OFEHATi^N,2 CELLS

              E-ACKWA5HING)
	PUMP STRLJCTUKiT:
    TYP TiuTC-K (


      i"- 10' t
                          ^;-,,,,^Yr^- --'"V-3
                                        ^ *£ ^'" I o' i  r' - p
               INFILTRATION BED INTAKE - PLANT  NO.  5309



                   FIGURE  ni-61
                         120

-------
                                                                        • PUVPHOUSE
BACKWASH PIPE
      GATE-
                                        •f3 • 12,500 GPV)'
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-------
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                  122

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have any direct impact on the waterway.  It would be competitive in cost
with conventional small intakes of the same capacity.  However, for very
large capacity requirements, several individual widely  scattered  cells
would be required and the cost would be substantially greater than for a
conventional  intake.  Radial well intakes have been in service for over
35 years and have been reliable.


Behavioral Intakes

The wide variety of behavioral intakes has been discussed  elsewhere  in
this report.  They represent a substantial departure from "conventional"
screen  facilities.   Such  intakes include horizontal screens, louvers,
air bubbles, sound, etc., and combinations of these features  with  each
other and with more conventional facilities.

Conventional  intakes  themselves  can  be modified to take advantage of
fish  behavior.   For  example,  angling  conventional  screens  to  the
incoming water flow can guide fish to bypasses in the same manner as the
horizontal screen and the louvers.  Figure 111-64 is a sketch of such an
installation.  The total facility will be substantially more costly than
the  more conventional setting due to the orientation of the screens and
the need for providing fish bypass facilities  (including fish pumps  and
auxiliary  water  cleaning equipment).  Hydraulic studies can be made to
develop guide walls both in front of and behind the screens to assure  a
reasonably uniform flow through screens.
                                123

-------
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                               SECTION IV

                              CONSTRUCTION

In t ro due t ion

The  adverse  environmental  impact  associated with the construction of
cooling water intakes results from three factors.  The first of these is
that the intake may occupy a finite portion of area in the  bed  of  the
source water body.  To the extent that this occurs, there will be a loss
of  potential habitat and a displacement of the aquatic populations that
reside at that location.  In addition, modifications to  a  larger  area
surrounding  the  specific  intake location, resulting from construction
activities and changes  in  existing  topography  can  create  permanent
disruptions in the biological community.

The  second factor is the irrpact on the ecosystem of increased levels of
turbidity resulting from the construction of the  intake  structure  and
any  associated inlet pipes and approach channels.  Turbidity levels can
also be increased as the result of  ercsion  of  inadequately  protected
slopes   of  excavations  and  fills  created  during  the  construction
operations.

The third factor  concerns  the  location  of  disposal  areas  for  the
materials  excavated  during  construction.  If spoil disposal areas are
located within the confines of the source water body, further  permanent
disruptions  of the existing aquatic species can result.  If these spoil
banks are not adequately stabilized, increased levels of  turbidity  may
persist for an indefinite period.  Adequate protection and stabilization
of  spoil areas located above the waterline are also required to prevent
long term erosion of these materials which can contribute  to  increased
turbidity levels.

Of  the  three factors mentioned above, the first will not significantly
impact the environment in most cases and will be discussed briefly.  The
remaining two factors can  create  serious  short  term  and  long  term
problems if not properly controlled.

Displacement of Resident Aquatic Organisms

The impact of the physical size of the intake on the displacement of the
resident  biological  community is a function of the size of the intake.
Offshore intakes which require long conduits  placed  in  the  waterbody
will  be more disruptive to the resident species than shoreline intakes.
The species that will be most effected by the construction of the intake
are the benthie organisms.  The impact  of  construction  activities  in
this  regard  is  expected  to be small since in no case will the intake
occupy more than a small percentage of the total  area  of  the  source.
All  water sources will be able to adjust rapidly to the loss of habitat
                                 125

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area and to reproduce the small  portions  of  the  important  organisms
lost.  If the locational guidelines proposed are followed, the impact of
this aspect of intake structure construction will be minimized.

Turbidity Increases

Increased   turbidity   can  result  from  the  construction  of  intake
structures in several ways.  First, increased turbidity can result  from
physical  construction activities conducted below the water level of the
source.  Such activities as dredging, pipe installation and backfilling,
and the installation and reiroval of coffer dams and  related  facilities
can  create  significant  increases in turbidity unless these activities
are  carefully  controlled.   The  turbidity  created  by  the  physical
construction  of  intakes  will  normally  be limited in duration to the
extent of the  construction  schedule.   The  impact  of  -his  type  of
turbidity  increase on the source ecology is dependent upon the particle
size   distribution   of   the   sediment,   the   sediment    transport
characteristics  of  the  source,  and  the  location  of  the important
organisms with respect to the intake construction activities.

There are a number of construction techniques that can  be  employed  to
reduce   the  turbidity  increases  associated  with  these  activities.
Excavation and dredging activities can be conducted  behind  embankments
or  coffer  dams to contain potential sediment discharges.  Care must be
exercised to limit the turbidity increases due to the  construction  and
removal of these facilities.  Onshore construction can be performed with
natural  earth  plugs left in place to prevent the discharge of material
to the source.  Construction can be scheduled to take advantage  of  low
water  periods and periods of reduced biological activity in the source.
Some sources will expose a large portion of the flood  plain  under  low
water conditions allowing much of the intake structure to be constructed
in the dry area.  Construction should also be scheduled around important
spawning periods, feeding periods and migrating periods to reduce impact
to these functions.

The  control  of  dewatering  activities  can  also  be  important.  The
discharge of soil materials from dewatering activities can be limited by
the use of holding ponds or filtration equipment prior to  discharge  of
this water to the stream.

All  material excavated or dredged in the construction of intakes should
be placed above the water line where possible.  The  laying  of  conduit
should  be  scheduled  to minirrize the amount of time that the trench is
open.  As soon as the conduit is placed, the trench  should  immediately
be  backfilled  and  the  surface of the trench smoothed over to prevent
errosion of the trench materials.

Long term  turbidity  increases  can  result  from  the  entrainment  of
material  from spoil areas located either below the waterline or erosion
of material  placed  above  the  waterline.   In  addition,  erosion  of
                                 126

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excavations  and  fills  that are permanent parts of the intake can also
add  turbidity  that  will  persist  long  beyond  the   completion   of
construction  activities.   Adequate stabilization of these fills may be
required which may necessitate rip-rap slope protection and  seeding  of
fill areas.

Disposal of Spoil
  — j- - .   —   . -1

The disposal of spoil within  navigable waters is controlled by the U.S.
Army ' Corps  of  Engineers.   The  disposal of spoil from excavation and
dredging  activities  can  displace  and   destroy   important   benthic
organisms.   The  disposal  of  spoil  in  knowm fish spawning, nursery,
feeding areas, shellfish beds and over important benthic populations can
cause permanent loss of important biological species.
                               127

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                               SECTION V

                       OPERATION AND MAINTENANCE
Introduction

The environmentally related performance  characteristics  o±  a  cooling
water intake structure will be primarily established by the location and
design  criteria discussed in the previous sections.  While most adverse
environmental impact will result from the operation of the intake, rela-
tively little can be done by the application of appropriate  operational
measures  to  significantly  reduce  such  adverse environmental impact.
This results from the fact that  during  operation  the  intake  is  the
passive  portion  of the cooling water system, which simply supplies the
water demand of the plant.  The only portions of  the  intake  structure
that  can  be  "operated"  are  the pumps and the screens.  Only a small
degree of improvement of adverse environmental impact can be effectuated
by controls placed on these facilities.

The development of a continuing enforcement and  performance  monitoring
program  might  be  of  some  value  in  determining desirable operating
conditions.

Maintenance is  an aspect of intake structure operation which has direct
environmental  impact.   Good  maintenance  will  require  an  effective
program  of  preventive maintenance for both above water and below water
portions of the intake.

Operation

Many conventional traveling screens are operated once during each  eight
hour  shift.  During periods of high debris loading in the water source,
screens may be operated more frequently and in some cases  continuously.
Pump  operation  is  directly  controlled  by  the water demand from the
plant.  Little flexibility in the operation of either of  these  systems
is possible.

Screen Operation

The  data   available  on   screen  operation   suggest that, under certain
conditions, continuous operation of the screens can  reduce  impingement
effects.    This  is  due   to  the  fact  that,  with  continuous   screen
operation,  fish are impinged for a shorter period of time.  One  of  the
primary  reasons  for  this  is  that   fish  typically   tend  to fight  a
situation which they recognize as perilous such as  being impinged  on   a
screen  or  being   lifted  out of water.  The  longer a fish is allowed to
fight such  a situation, the more likely it is to damage  itself.
                                  129

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Continuous screen  operation  to  reduce  impingement  effects  is  only
applicable  where  fish  separation and bypass systems are available.  The
number of installations having this  capability  is  small.   Continuous
screen operation will shorten screen life and increase maintenance costs
to some degree.

Pump Operation

Control  of  pump  operation has been used at certain intakes (Plant No.
3608) in the northern latitudes to reduce impingement effects during the
winter months.  This type of  control  involves  the  reduction  of  the
volume of water pumped during these cold water periods.  Pump flows  can
be  reduced  without  detrimental  effect  on plant performance if water
temperatures are low enough to compensate  for  the  reduced  volume  of
cooling water.

Since  fish  swimming ability for many species is drastically reduced at
low water temperatures, such a flow reduction in the winter  period  can
effectively  reduce  fish  impingement.   The  best  way to reduce water
intake volumes is to reduce the pump speed.   This can only be done where
pumps have variable speed drives.  Unfortunately, most circulating water
pumps do not have variable speed capability.   Another way to reduce  the
intake  volume  is  to  shut  down  a  pump.    This will cause increased
velocities through the remaining screens  because  of  the  pump  runout
factors noted in the design section of this portion of the report.

On  new  structures  the value of a reduced number of pumps operating in
winter should be evaluated and considered in  the overall initial design.

Performance Monitoring

For  several  reasons,  the  development  of   a  continuing  performance
monitoring   program   in  conjunction  with   the  operation  of  intake
structures  would  be  helpful.    First,  the  data  developed  on   the
performance   of   various   intake  systems   under  different  regional
conditions could be used  to  develop  a  base  on  intake  performance.
Second,  it would allow the effectiveness of individual intaxe guidelines
to  be determined and periodic updating of individual requirements where
desirable.


The following type of data would be included:

- source water temperatures
- Stream flows (where applicable)
- Screen operaton schedules
- Cooling water flow
- Number,   types  and  condition  of  important   organisms   impinged,
entrained, and bypassed.
                                 130

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Maintenance

An  effective  preventive  maintenance program can be developed for both
below water and above water portions of the intake structure.

The maintenance of the above water portion of the intake will  basically
consist  of  the  maintenance cf the mechnical equipment associated with
the intake.  This equipment includes primarily the  screens  and  screen
drives, the trash racks and supporting equipment.

Suggested preventive maintenance procedures are normally supplied by the
manufacturer  of  the  various  systems.   This  program will consist of
regular lubrication schedules for all rccving parts and a firm inspection
program to check key  wear  points,  particularly  screen  basket  lugs,
headshaft  lugs,  carrying  chains,  etc.   Inspection of the spray wash
system should also be made on a regular basis with  particular  emphasis
on  the  condition  of  the  spray  nozzles.  The water screen should be
tested for binding and misalignment on a monthly basis by operating  the
screen  for  several  revolutions with the test shear pin left in place.
Adequate maintenance procedures also require the  stocking  of  a  spare
parts  inventory  because  of  long  lead times which generally exist on
spare  parts  deliveries.   The  suggested  list  of  spare  parts  will
generally be supplied by the equipment manufacturer.

Preventive maintenance of the portion of the intake below tne water line
is  also  important and also often neglected because it usually requires
the dewatering of the individual  intake  bays  and/or  use  of  divers.
Below  water  maintenance  should include visual inspection of footwells
and footwell bushings on an annual basis.  This may require a  diver  if
the  well  cannot  be  dewatered  or  the  screen  raised.  In addition,
periodic below water inspection cf the intake can reveal the  extent  of
the following adverse conditions as noted in Reference 76:

   Silt  accumulation in front of the structures which can effect intake
hydraulics.

- Undermining of the base of the structure which might cause  subsequent
collapse of the structure.

- Deterioration of stop log and screen guides.

   Spalling  concrete  which  may expose reinforcing bars and weaken the
structure.

- Damage to pump impeller and fittings which can lead to pump failure.
                                 131

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                               SECTION VI

                               CCSI DATA

Introduction

This section  contains  cost  data  relative  to  cooling  water  intake
structures.  The section is organized tc first present current costs for
the  construction of the several types of conventional intake structures
commonly used by industrial establishments.  This is done to establish a
baseline  against  which  the  additional  costs  associated  with   the
implementation  of  the control measures can be compared.  Following the
development of this baseline cost data, estimates are made of the  costs
associated with the certain intake structure control measures.

The  cost  data  contained  in this section are capital costs associated
with  intake  structure  construction  only.   No  consistent  data   on
operation  and  maintenance  of  cooling  water  intakes were available.
Records of these costs are not routinely kept by either the users or the
manufacturers of intake structure equipment.   The  magnitude  of  costs
associated  with  operation  and  maintenance  of  cooling  water intake
structures are believed to be small.

A further qualification  of  the  data  contained  in  this  section  is
required.   The  scarcity  of  detailed  data on the constructed cost of
intake structures was the major problem area in the development of  this
document.   This  lack  of  data  results from the fact that most intake
structures are constructed as part of a larger  general  contract  which
includes  other  structures on the site, and in some cases, the complete
plant.  It is difficult in these cases to separate the  portion  of  the
costs that are directly associated with the intake structure either from
the bid package or from field records of the cost of construction put in
place.  it was necessary therefore to synthesize the cost data available
from  several  sources.  In doing this, the costs of intakes constructed
at ditferent dates and in different geographical areas  of  the  country
arp  combined  without  normalization of the data with respect to either
inflationary factors in the  construction  market  or  well  established
regional  cost  differences.   The cost data presented must therefore be
considered to be order of magnitude costs and should  be  used  in  this
context only.

Cost of Construction of Conventional Intake Structures

The  cost  of  conventional  intake structures is influenced by both the
type of intake and the size of the intake facility.   The  cost  of  the
major  piece  of mechanical equipment in the intake, the traveling water
screen, contributes a relatively  small  portion  of  the  total  intake
structure cost.
                                133

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Screen Costs

The  costs of furnishing and installing intake water screens are readily
available from any of the leading screen manufacturers.  Table Vl-1 is a
tabulation of  the  cost  of  16  conventional  traveling  water  screen
installations  provided  by  a  leading screen manufacturer during 1971.
These costs have been converted to a unit flow  basis  and  the  results
tabulated  in  the  next  to the last column of the table.  The approach
velocity for each installation is recorded  in  the  last  column.   The
factors  that  most  effect  the  cost  of  the screens are tne approach
velocity and the size of the plant.  The total range of screen cost  was
from $2,000/m3/s ($0.13/gpm) to $37,40Q/m3/s ($2.36/gpm) .  The effect of
approach  velocity  was  pronounced  with  the  average  unit  cost  for
installations where approach velocity exceeded 0.3  m/s   (1  fps)   being
$5,200/m3/s  ($0.33/gpm)   compared to a cost of $16,600/m3/s (*1.05/gpm)
for installations where the approach velocity was less than 0.3  m/s  (1
fps).   The  variation  with the size of flow was even more significant.
The cost of large screening units  (greater than 6.3 m3/s  (100,000  gpm)
per  screen averaged $3,200/m3/s ($0.20/gpm) as compared to #17,400/m3/s
($1.10/gpm)  for smaller units (less  than  3.2  m3/s   (50,000  gpm)  per
screen.

Intake Structure Costs

Estimated  cost  data for the three different types of intake structures
are shown in Figure VI-1.  These data were taken from Reference  11  for
small  powerplants  and  from estimated costs of individual large plants
from various sources.  The base year fcr these cost data is  1971.   The
figure   demonstrates  the  two  important  cost  impacting  factors  in
conventional intake construction.  The first of these  is  the  type  of
intake  used.   The  offshore intake will ccst significantly more in all
size ranges than either the shoreline intake or the channel  type.   The
basic  reason  for this is the cost of excavation and laying of offshore
conduit.  The cost differences between the channel type  of  intake  and
the shoreline intake appear to be small except in the lower size ranges.

The other significant cost factor is the size of the plant.   The cost of
construction of all three types of intakes are shown to be significantly
higher  for  smaller  plant  sizes  than  for  larger  powerplants.  For
instance, the costs of offshore intakes are shown in Figure VI-1 to vary
from as low as $3/KW of installed electrical generating capacity  for  a
1000-MW plant to as high as $90/KW for plants under 10 MW.

The  data contained in the Figure have been standardized on the basis of
significant cost factors.  The length of pipe used in the development of
the curve for offshore  intakes  was  975  M  (3200  ft).   Likewise,  a
constant  127,700  m3 (167,000 cu yds)  of excavation was assumed for all
channel intakes.  The amount of these items and  their  costs  can  vary
significantly.    Reference  24 shows the costs of three offshore intakes
constructed between 1955 and 1958.   The  cost  of  installation  of  the
                                134

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Ln
                                                  TABLE VI-1





                                    COST  OF TRAVELING WATER SCREENS  (1971)
Plant
Code
No.
4709
1243
4817

N.A.
4001
4829
N.A.
2110
1003
1731
1002
0616
0108
0109
N.A.
N.A.
Number
of TWS
6
1
4

6
4
3
2
1
8
3
2
1
3
2
6
1
Basket
Size
(m)
4.
1.
2.

3.
3.
3.
1.
3.
3.
3.
3.
3.
2.
2.
3.
1.
27
52
13

05
05
05
52
05
05
05
05
05
44
74
05
78
Centers
(m)
17.98
7.01
9.75

11.58
10.58
13.72
5.18
31.39
10.97
11.89
6.40
9.45
19.81
10.06
8.84
11.58
Type Flow Design Low
of per TWS Water Depth
Water m-^/s m
Fresh
Fresh
Salt or
Brackish
Fresh
Fresh
Salt
Salt
Fresh
Fresh
Fresh
Brackish
Salt
Fresh
Fresh
Salt
Salt
11.91
.94
4.50

7.91
5.36
8.14
1.03
4.72
3.20
8.63
2.90
6.93
2.19
0.69
1.73
1.26
8
1
5

6
5
6
2
5
6
8
3
4
5
4
3
2
.53
.68
.18

.70
.49
.25
.74
.79
.19
.53
.05
.11
.33
.72
.35
.40
Frame Approx .
(No Posts) Cost
$
4
2
4

2
2
2
4
4
2
2
2
2
4
2
2
2
228,
16,
120,

144,
84,
87,
33,
49,
197,
53,
30,
29,
93,
52,
137,
23,
000
000
000

000
000
000
000
000
000
00
000
000
000
000
000
000
Unit
Cost
$/m3/s
3,200
17,000
6,700

3,000
3,900
3,600
16,000
10,400
7,700
2,000
5,200
4,200
14,200
37,400
13,200
18,300
Velocity
m/s
0.326
0.369
0.409

0.387
0.320
0.427
0.244
0.268
0.171
0.332
0.305
0.549
0.168
0.052
0.168
0.290

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    100
o
u
t/)
(0
-p
                                   Offshore Intake     975  m  long


                                   Channel Intake   127,700 m3 dredged
                      Off SHOlZt lU7AVi6r
              100   200   300   400    500    600   700   800   900    1000


                                       Size (MW)




                            COST OF INTAKE SYSTEMS



                                 FIGURE  VI-1
                                          136

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offshore  piping  for  these  powerplants varied from as low as $2.16 to
$4.70 per KW installed.  Caution is therefore suggested in  the  use  of
this  figure.   Costs  of each type of intake can vary considerably from
the curves shown.

Additional  data on the cost of shoreline intakes are contained in Table
VI-2.  The Table  contains  cost  data  on  five  cooling  water  intake
structures  and  four  makeup  water intake structures constructed after
1965.  With the exception of three makeup water structures the cost data
contained in the table represenr constructicn  actually  put  in  place.
The  costs of the three makeup water intakes are detailed cost estimates
since these plants are now still  under  construction.   Tne  cost  data
contained  in  rhe  table  are substantially the same as in Figure VI-1.
The cost of shoreline intakes runs from between $l-$4/KW ±or the  larger
size powerplants.   The cost differences between makeup water systems and
circulation  water  systems  does  not  appear, from the Table, to be as
great on a $/KW basis as the difference  in  intake  flow  volume  would
indicate.   The  cost data, on a flow basis, appear to range from $40 to
$90 per gpm of flow for makeup water intakes and from $6 to $30 per  gpm
of  flow for circulating water intakes.  For both these types of systems
the upper cost ranges are for nuclear powerplants.  The nuclear  service
intakes, although pumping much smaller volumes of water, are becoming as
large  as  the  circulating  water intakes in order to accomodate backup
equipment, provide missile protection and insure operation under maximum
probable storm, water flood and drawdown levels.  The data presented  in
Table  VI-2  can  be  compared  to  the screen cost data on the basis of
$/m3/s  ($/gpm).  It can be seen that  the  cost  of  the  screens  is  a
relatively  small portion  (less 1-2%) of the intake structure cost.  The
bulk of the cost of intakes are associated structural  features, and are
relatively independent of equipment costs,  at  least  for  conventional
intakes.

Typical rule of thumb estimating guides for intakes are the following:

   Water screens cost approximately $ll/m2  ($1.00/ft2) of
   screen surface with a range of $5.50 to $24.22/m2
    ($.50 to $2.25/ft2) .

-  The cost of construction of offshore pipeline can vary
   from as low as $500/m  ($150/ft) for small makeup water
   lines to as much as $6,600/m ($2,000/ft) for large maxeup
   water lines.

   The cost of shoreline intakes will average approximately
   $ll,000/m2  ($l,000/ft2 27i based on the cross-sectional
   area of the screens.

   Shoreline intakes will also vary from between $140 to
   $424/m3  ($4 to $12/cu ft) of structure enclosed beneatn
   the operating deck with a mean of $212/m3  ($6/ft3).
                                   137

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                                                  TABLE  VI-2
                                          COST OF INTAKE  STRUCTURES
CD
Plant
Code
No.
5404
5309
4213
3407A
3407
3805
Unit 1
3805
Unit 2
3601A
3113
Intake
Flow
m3/s
1.26
1.58
1.58
2.27
20.79
4.85
5.67
20.79
20.16
Total
Cost
$
466,000
2,000,000
2,500,000
5,000,000
1,000,000
400,000
950,000
4,800,000
8,700,000
Unit
Cost
$/m3/s
369,800
1,265,800
1,582,300
2,202,600
48,100
82,500
167,500
230,900
431,500
Unit
Cost
$/kw
0.40
1.82
1.37
4.17
1.78
1.67
2.26
4.00
11.18
i
Plant
Fuel
Fossil
Nuclear
Nuclear
Nuclear
Nuclear
Fossil
Fossil
Fossil
Nuclear
Comments
Intake
Type
Makeup
Makeup
Makeup
Makeup


Year
Commissioned




Circulating
Water
Circulating
Water
Circulating
Water
Circulating
Water
Circulating
1965
1976
1975
1977
1965
1966
1973
1972
1972
                                                                                         Water

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                     PrQBQged_Gu_idelines

Locational Measures

The  measures  which potentially have the greatest cost: impact on intake
structures  are  concerned  with  the  location  of  the   intake.    In
particular,  where locational measures involve extensive offshore piping
at a site for  which  a  shoreline  intake  would  have  otnerwise  been
suitable,  the  intake  cost  can  be increased significantly.  Costs of
offshore piping have been detailed above, and it was snown that the cost
of this work can increase the intake cost significantly.

Design Measures

The design measures that will increase  costs  significantly  are  those
that  involve   a  reduced  approach  velocity and flush mounting of the
screens.  The changes that could be involved are shown in  Figures  VI-2
and VI-3.  These figures are based on a certain design of a hypothetical
shoreline  intake* structure  without  the  modifications required.  The
unmodified design provides an approach velocity of 0.6/m/s (2 fps)  with
screens set back from the front face of the intake.  The modified design
amploys an approach velocity of 0.15 m/s  (0.5 fps) with screens   set  at
the  front  of  the  intake  and  fish  passageways provided berween the
screens  and  the  trash  racks.   The  total  intake  xlow-per-bay   is
approximately 10.1 m3/s  (160,000 gpm)  at maximum pump runout conditions.
The  intake  would  draw an average of 15.8 m3/s  (250,000 gpm) using two
bays with the third bay acting as a spare.  This flow is  equivalent  to
the  circulating  water flow for a fossil-fired plant with a capacity of
approximately 300 MW.

The major changes involved include the increasing of the volume   of  the
intake  structure  below  the  operating  floor  from approximately 1190
m3 (42,000  ft3) as shown in Figure VI-2 to approximately 2040 m3   (72,000
ft3)  as   shown  in  Figure  VI-3.  The cost increase involved in making
these changes are shown in Table VI-3.

                              TABLE VI-3

     COST ANALYSIS - IMPLEMENTATION OF EXAMPLE DESIGN REQUIREMENTS

                      Unmodified Intake      Modified Intake
  Facility            	Cost	      	Cost	

Structure              $ 189,000              $ 324,000

Racks                     17,000                 38,000

Traveling Screens         54,000                 80,000


    TOTAL              J  260,000              $ 442,000
                                   139

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                         17.5m (581)
                   Screens
ffi
o
rt
QJ
rt
CD
h!
Hi
O
0
D
        ".«'-'«  «>
           n..
       *•  s '  • *  -
                     JT<
                    PLAN
                                       Pumps
                ELEVATION
                                                            U1
                                                            3
                                                            KJ

                                                            Ul
                                                Total  Flow
                                                           60m3/S
                                                 (160,000  gpm)
                                               Approximate  Volume
                                               below the  operating
                                               floor: 1189  m3
                                                      (42,000  cubic feet)
         DESIGN  OF CONVENTIONAL  INTAKE


                  FIGURE VI-2
                       140

-------
                            18m (60V
•>
   T, W   V
0.15mps ——

 (0.5  fps)
             a
                      rn mm
                         1

              n,
                         O
                         s:
                        1111
                                                          B
                                                          ±~.
                                                          NJ
                                                    t.
                                                          |ro
                                                          loo
                                                          I
              O

              -J
              LH
              3

              to

              Ul
                    r^a
                       Shoreline (sheet pile waterfront wall)


                            PLAN


                                                  Total Flow
             [-) 9m(3C
                      -. .». ./Lf
                                + 3.2m (10.5';
                                     3
                                                              (160,000  gpm)
n
                                          <->n
                                          3m (20 ')
                                                 Approximate Volume

                                                 below the operating

                                                 floor:  2040m3

                                                       (72,000 cubic feet)
                              ELEVATION
        DESIGN OF CONVENTIONAL INTAKE MODIFIED BY RECOMMENDATIONS


                              FIGURE VI-3
                                      141

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The total cost increase involved in making these changes is shown in the
Table to be approximately $182,000 or roughly 70% of  the  cost  of  the
unmodified intake.

In  addition,  the  larger  structure  requires  more  dredging  and the
construction of a sheet pile retaining wall upstream and  downstream  of
the  intake  to  provide  continuity  to the "flush-face" intake, and to
facilitate flow through the fish passage  between  the  trash  rack  and
traveling screens.  The estimated cost for the additional work (dredging
and retaining wall)  is $90,000.

The   estimated  cost  of  modifying  the  traveling  water  screens  to
incorporate fish handling and bypass systems as discussed in the  design
section of this portion of the report is between $15,000 and i20,000 per
bay  depending  on  the  screen  size.   An  equivalent  amount could be
required to provide  the  additional  screen  wash  systems  and  bypass
systems required.

Costs - Other Measures

There  will be additional costs for measures related to construction and
performance monitoring.  The costs of these measures are  indeterminable
at this time, but are not believed to be excessive.
                                 142

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                              SECTION VII

                 CONCLUSIONS AND RECOMMENDED TECHNOLOGY

                     TO BE CONSIDERED IN EACH CASE


Introduction

This  section  summarizes  the  findings  of  the  previous  sections on
background,  location, design, construction and operation and maintenance
of cooling  water  intake  structures.   The  format  for  -this  section
presents  certain  conclusions  with  respect  to  the  various  factors
involved.  The technology dicussed herein were prepared to assist in the
evaluation of the best technology available for minimizing environmental
impacts of cooling water intake structures.  As a minimum, the following
recommended technology should be considered in each case.

Background

It was concluded  that the application of the best technology  available
on  intake  structures  alone  will  do  little  to  protect against the
entrainment effects on small organisms passing through a cooling system.
These effects are better controlled  ty  either  controlling  the  plant
intake flow or  the design of the  cooling water systems.  Such measures
do  not relate to cooling water intakes per se, and therefore are beyond
the scope of this report.

It  was  found  that  some  intakes  have  been  designed  without   the
development  of  adequate data on the biological community that would be
affected by intake operation.  Since subsequent measures  for  location,
design  and  construction  can  only  be  made  on  the  basis  of  this
information, this data base should be developed in each case.

Technology - Acquisition of Biological Data

    The discharger should provide data on the biological community to be
protected.  In some cases, depending on the severity of the problems and
especially for new steam electric  powerplants  withdrawing  water  from
sensitive  water  bodies,  the data should consist of, as a minimum, the
following:

- The identification of the major aquatic species in the water
  source.  This should include estimates of population densi-
  ties for each species identified, preferably over several
  generations to account for variations that may occur.

- The temporal and spatial distribution of the identified
  species with particular emphasis on the location of spawn-
                                  143

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  grounds, migratory passageways, nursery areas, shellfish
  beds, etc.

- Data on source water temperatures for the full year.

- Documentation of fish swimming capabilities for the species
  identified, and the temperature range anticipated under test
  conditions that simulate as close as possible the conditions
  that exist at the intake.

- Location of the intake with respect to the seasonal and diurnal spatial
  diurnal spatial distribution cf the identified aquatic species.


Location

The proper location of the intake structure with respect to the  aquatic
environment is far and away the most important consideration relevant to
applying  the best technology available for cooling water intakes.  Care
in the location of the  intake  can  act  to  grossly  minimize  adverse
environmental  impacts.   It will be difficult and perhaps impossible in
certain cases to offset the adverse  environmental  impact  of  improper
intake  location  by subsequent changes in either design or operation of
the intake structure short of significantly reducing the intake volume.

Therefore, it is critical that the qualifications of the biological  and
other  investigators  and the data obtained, especially as a preliminary
to the location of  a  new  intake,  reflect  the  significance  of  the
decisions which must rely on the results of the study.

Intake Location With Respect to Plant Circulation Water Discharge

The  potentially  adverse effects of the recirculation of water from the
discharge back to the intake have been discussed.  Most powerplants will
prevent this to maximize plant thermal efficiency.  In some cases  where
this  is difficult to do, some recirculation may be tolerated.  From the
environmental standpoint, recirculaticn of warm water is undesirable.

Technology - Prevention of Warm Water Recirculation

All intakes should be located with respect to the plant, discharges in  a
manner  that  will  prevent,  to  as  great  an  extent as possible, the
recirculation of warm water from the discharge back to the intake.

Plant and Vertical Location of the Water Inlet

The location of the water inlet with respect to the temporal and spatial
distribution of  the  resident  and  migratory  aquatic  populations  is
extremely  important.   Intake configuration can be selected to withdraw
                                 144

-------
water from any point in the source water body.  Inlets can be located to
draft water from any elevation in the source.

Technology - Location and Elevation of Water Inlet

Water inlets should be designed to withdraw  water  from  zones  of  the
source that are the least productive biologically and contain the lowest
population  densities  of the critical aquatic organisms.  This includes
both the plan and location of the inlet and the vertical location in the
source water body.

In addition, inlets should be located to avoid spawning  areas,  nursery
areas,  fish migration paths, shellfish beds or any location where field
investigations have revealed a high concentration of aquatic life.

The location of the intake should alsc be selected to take advantage  of
river  or  tidal currents which can assist in carrying aquatic life past
the inlet area or past the face of the screens.


Intake Location With Respect tc the Plant

The incremental impact on entrained organisms is directly related to the
transit time  between  the  intake  and  the  condenser.   However,  all
entrained  organisms  would be lost, anyway, in configured recirculating
cooling water systems.  Therefore, for  other  types  of  cooling  water
systems  the  intake  should  be  located  close  to  the  plant.   This
consideration is even more important in the  relative  location  of  the
outfall structure and the plant.

Technology - Location of Intake With Respect to the Plant

For  nonrecirculating  cooling water systems the intake structure should
be located close to the plant.
The basic conclusion related to the design section is that there  is  no
generally  viable alternative to the conventional traveling water screen
available at the present time.  Some new screen types have recently been
developed that might prove  to  have  generally  superior  environmental
characteristics  following  an  adequate  period of testing.  Certain of
these designs might be superior today at certain  sites.   It  is  noted
that  this  is one area in which research and development  have not kept
pace with the need.  Research projects directed toward  the  development
of  more  effective  screening  systems  could  have  valuable  results.
Furthermore, since the configuration of the intake is largely determined
by the screening system employed, the conventional intake structure will
probably remain substantially unchanged in the near future.
                                 145

-------
Therefore, most of the design recommendations  contained herein are based
on the configuration and physical design  features of conventional intake
structures as previously defined in Section III.  It is anticipated that
new^intake designs will emerge that may have more positive environmental
design features than  the  conventional   intake.   One  of  the  express
overall   recommendations   is   the   encouragement  of  this  positive
evolutionary process in the technology.   As  dicussed  in  Section  III,
some  of  the  new  technologies  that will influence intake design have
already been partially explored.  These include  the  increased  use  of
behavorial barriers such as the louvered  intakes; the development of new
types  of  physical  screening systems such as the horizontal travelling
screen; and the increased use of bypass systems.  The present status  of
these  technologies and their very limited use at existing cooling water
intake structures does not justify separate  recommendations  for  these
types  of systems at the present time.  However, certain features of the
following recommendations may be applicable to these types  of  systems,
as well as to conventional intake structures.

Approach Velocities

Typical  approach  velocities to the traveling water screens at existing
intakes fall within the range cf about 0.24 to  0.33  mps  (0.8  to  1.1
f ps) .

Technology - Design Approach Velocities

The  design  approach  velocity  to  the  intake water screens should be
measured in the screen channel upstream from the screens and be based on
the effective portion of the  screen  face.   The  velocity  measurement
should  further  be  based  on  the lowest water level anticipated.  The
design approach velocity should be conservatively based on data specific
to the design organism(s)  at the intake  location.    These  data  should
include as a minimum:

- The spatial and temporal distribution of the fish by size
  for each species identified.

- The annual temperature range anticipated at the intake.

- The demonstrated avoidance capability of these species over
  the full range of temperatures experienced.

It is possible that a low approach velocity could have a more
adverse environmental impact than a higher approach velocity.

Uniform Approach Velocities and Effective Screen Areas

The  maintenance  of uniform velocity profiles across the  screen face is
an important feature in effective screen performance.   Many factors  can
influence  the  velocity  gradient  at  the  screen face and it is  not a
                                146

-------
simple task to  eliminate  non-uniform  velocities.    Another  important
consideration  is  the determination of the effective area to be used in
determining the approach velocity.   In many cases,  the effective area is
significantly less than the full submerged area of  the screen.

Technology - Uniform Approach Velocities

The discharger should document that effectively uniform velocities  will
be  maintained  across  the face of the screen at the design conditions.
The discharger should also indicate the effective screen  area  used  in
the  approach  velocity  calculation.  Where there  is reason to question
this information, hydraulic model testing, as well  as  velocity  profile
measurements taken at the intake should te required of the applicant.

selection of Screen Mesh Size

The  selection  of  screen  mesh  size is generally based on providing a
clear opening of no more than one-half of the  inside  diameter  of  the
condenser  tubes.  The powerplant industry has generally standardized on
0.95cm(3/8") mesh size.  While this criteron may be adequate for keeping
foreign objects out of the cooling system,  this  criteria  may  not  be
adequate for proper proection of all aquatic species.  A rational design
approach  for  screen  mesh selection based on the design organism(s) is
contained in the design portion of the report.  The data  used  in  this
approach  are  not considered extensive enough for development of a firm
recommendation on screen mesh size.

However, this approach may  be  used  in  lieu  of  better  data.   More
information  on  this aspect of screen design should become available in
the future as the biological data required above are developed.

Behavorial Screening Systems

None of the available behavorial  screening  systems  have  demonstrated
consistently high efficiencies in diverting fish away from powerplant or
other  industrial  intake  structures.  The behavorial screening systems
based on velocity  change  appear  to  be  adequately  demonstrated  for
particular  locations  and  species,  at least on an experimental basis.
More data on the performance of large prototype  systems  at  industrial
plants  will be required before the louver system can be recommended for
a  broad class of intakes.  The "velocity cap" intake can be  recommended
to  be  considered  for all offshore vertical intakes since it would add
relatively little to the cost of the intake, and has been  shown  to  be
generally effective in reducing fish intake to these systems.

The  performance  of  the  electric screening systems and the air bubble
curtain appears to be quite erratic, and the mechanisms governing  their
application  are  not  fully  understood at the present.  Tnese types of
systems might be experimented with in  an  attempt  to  solve  localized
                                 147

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problems  at  existing  intakes,  since the costs involved in installing
these systems are relatively small.

No  successful  application  of  light  or  sound  barriers   has   been
identified.   It  appears  that fish become accustomed to tnese stimuli,
thus  making  these  barriers  the  least  practical  of  the  available
behavorial systems on the basis of current technology.

Technology - "Velocity Cap" Intakes

All  offshore intakes should be fitted with a "velocity cap" designed to
minimize the intake of the design organism (s) that are resident  at  the
individual  intake  location.   The design approach velocity measured at
the face of the intake opening should conform  to  the  design  approach
velocities previously discussed.

Physical Screening Systems

It  is  concluded  that  the  conventional  traveling  water screen will
continue to be widely used at powerplants for the  near  term,  although
this  system may have some potentially significant adverse environmental
features.

Furthermore,  the  fixed  screening  systems  currently   installed   at
powerplant  intakes,  have  potentially even more damaging environmental
characteristics.  These systems invariably  involve  longer  impingement
periods between cleaning cycles and increased damage to the fish because
of  greater  local velocities across the more completely clogged screen.
The crude methods employed to clean fixed screens are also  damaging  to
fish.

Technology - Limitation of the Use of Fixed Screens

The use of fixed or stationary screening systems should be prohibited at
powerplant  intakes.  The cost impact of this would be relatively small,
since the higher initial cost of rotating equipment will  be  offset  by
the  reduced  labor required for manual cleaning of the screens over the
lifetime of the intake.

Fish Handling and Bypass Facilities

There is  some  evidence  to  recommend  that  all  new  intakes  should
incorporate  a fish handling and bypass system which will allow for safe
return of important fish species to the  water  source  along  with  the
physical screening system.  Unfortunately, the case of fish handling and
bypass systems in conjunction with cooling water intakes is not a highly
developed   technology  at  the  present  time.   Therefore,  a  blanket
recommendation, requiring these systems at all  new  intakes  cannot  be
recommended, but this technology should be considered in such case.
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The  use  of  fish  bypass  facilities  at  existing  intakes where fish
impingement has been documented may improve  the  performance  of  these
intakes.   These  types of facilities may also be desirable in those new
intakes where it is not clear that impingement can be avoided.  One type
of bypass system can be incorporated in the  conventional  intake  using
the  traveling  water  screen.   This  system  assumes  impingement  but
minimizes its effect in the following manner:

- Impingement time is reduced by continuous operation or rhe
  screens

- It provides a means for a gentle separation of the fish
  from the screen mesh

- It provides a passageway for safe return of fish to the water
  way

One installation of this type is presently being installed  on  a  major
powerplant  intake   (Plant  No. 5111)  and was described in detail in the
design section of this report.  The basic features of  this  system  are
shown  in  Figure III-U1.  It is believed that this type of system might
have a positive impact on the impingement problem if the performance  of
this  initial  installation  is successful.  However, this system is not
sufficiently developed at present  to  provide  a  basis  tor  a  formal
general recommendation.  The progress of this type of facility should be
closely  followed  in  the  future  because  the  system appears to have
attractive environmental features.

Control of Fouling and Corrosion

Biological fouling of the cooling water system downstream of the  intake
is  usually controlled by the addition of chlorine to the cooling water.
The point of application is often the intake structure.  The application
of chlorine at the intake  can  adversely  affect  any  subsequent  fish
bypass  system  that may be installed.  It is, therefore, important that
if chlorine is to be administered at  the  intake  it  should  be  added
downstream  of  any  such  facility.   It  is noted that the addition of
chlorine at this point will seriously affect the survival chances of all
entrained organisms, and its  use  should  be  carefully  monitored  and
controlled.

Corrosion  protection  of the screening system is not a design factor of
intakes that directly affects  the  environment.   It  will  be  to  the
advantage  of  the owner to insure the integrity of screening systems by
providing adequate materials for the type of use and  water  quality  of
the source.
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Intake Configuration

Of the three conventional intake structure types discussed in the design
section  of  this report,  the approach channel type of intake generally
has sufficient potential for environmental  impact  to  warrant  careful
evaluation  prior  to  its  use.  This type of intake is shown in Figure
111-47.

Technology - Use of Approach Channel Intakes

The use of lengthy approach channel intakes should be avoided  where  at
all  possible.   Where  they  are used, the screening facility should be
located as close as  possible  to  the  shoreline  while  maintaining  a
satisfactorily  uniform  velocity distribution.  An arrangement is shown
in Figure 111-48.  The  velocity  in  the  approach  channel  should  be
limited to the design approach velocity.

There  are  further  considerations in the design of a shoreline intake.
In some cases at nuclear powerplants, it may not practical,  for  safety
reasons,  to  locate  the  screen  structure or intake on the shoreline.
Also, the placement of the intake with respect to the shoreline,  should
be such as to limit the protrusion of the intake into the stream, except
in  the  case  of an ocean site.  Protuding intakes cause localized eddy
currents that can affect the travel of fish to the intake.   An  example
of this type of design is shown in Figure 111-49.

Technology - Limitation of Protruding Shoreline Intakes

Intakes  should  be  designed  to  limit  the  protrusion  of the intake
sidewalls in the stream.

Another important design consideration  for  shoreline  intakes  is  the
location  of  the  screens within the confining sidewalls of the intake.
Most conventional intakes have the screens set back from the face of the
intake between confining sidewalls.  This type  of  setting  can  create
undesirable  entrapment  zones  between the trash racks and the screens.
The recommended setting is to mount the screens  flush  with  the  front
face  of  the intake as shown in Figure 111-50.  In this type of design,
it is also desirable to design the trash racks to allow fish passage  in
front  of  the screens.  This type of intake is most suited to locations
where there is sufficient current in the source to wash  the  fish  past
the  intake.   Two  examples  of  this  type  of  design incorporated in
existing powerplants are shown in Figures 111-51  (Plant  No.  3601)  and
111-52  (Plant No.  0610).

Technology - Screen Settings for Shoreline Intakes

The  screen  settings  for  all  shoreline  intakes  should  provide for
mounting the screens flush with the upstream face  of  the  intake.   In
addition, provisions should be made for fish passageways located between
the screens and the trash racks.
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Use of Walls

Walls  are  often  used  to select water from the coldest portion of the
source.  The use of a  wall is shown in Figure III-4.   Walls  not  only
create non-uniform velocity conditions at the screens, but also create a
dead  area  where fish can become entrapped.  Fish will nor usually swim
back under the wall to safety.  It is  recommended  that  this  type  of
construction be avoided.

Technology - Limitation on the Use of Walls

The  use  of  walls  for  the  purpose of selecting ccld water should be
avoided.  Walls may be used where required to prevent the  recirculation
of  warm  water  or  to select water from biologically safe areas of the
source.  Both of these factors are contained in previous guidelines.

Pier Design

Many intakes utilize a pier which protrudes upstream of the screens  and
serves  as  a dividing wall between adjacent screen channels.  This type
of design is shown in Figure 111-53, and  is  not  consistent  with  the
concept of flush mounting of screens  and should therefore not be used.

Pump ;to Screen Relationships

The  relationship of the pump capacity to the screen area provided is an
important design factor at intake structures.  Several intake variations
to accomodate pumps of a wide range of sizes is shown in Figure  111-56.
Care  must  be  taken to locate the screen with respect to the pump in a
manner which will properly utilize the entire screen surface.  Any  mis-
match  between  screen  size  and  pump  size  can result in undesirable
velocity distribution across the screen.  Hydraulic Institute  Standards
recommend  minimum  distances  from  screen  to  pump as well as lateral
dimensions of the screen and pump wells.  However, these recommendations
are based on pump performance criteria and not best utilization  of  the
screen area.

Another   important   design  consideration  is  the  effect  on  screen
velocities under pump run-out conditions.  This condition  exists  where
one  pump  is  removed  from  service  and the total dynamic head on the
remaining pumps is reduced.  Flow through the remaining screens  may  be
increased by as much as U0% above average design conditions.

It  is  impossible  to establish a uniform recommendation that would re-
flect the different problems that might arise  because  of  the  several
pump-screen  relationships  that  exist.  However, dischargers should be
required to show how their designs have allowed for these factors.
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Ice Control Facilities

Most  intakes  located  in  the  northern  latitudes  employ  a  partial
recirculation  of warm condenser discharge back to the intake to control
ice buildup in front of the intake.   The potential adverse environmental
effects of warm water recirculation have  been  well  documented.   Fish
will  be attracted to the intake in the winter months.  At tne low water
temperatures their swimming capability will be greatly reduced  and  the
possibility of their entrapment in the intake will be increased.

Unfortunately,  there  is  no alternate ice control technology currently
available to replace hot water recirculation.   Submerging  the  intakes
can  create  another problem as noted in an earlier section.  Air bubble
systems have not been proven on large cooling  water  intakes,  although
they may becoma acceptable following a further period of development.

The development of alternate technology for the control of ice at intake
structures  is  one area in which further research should be undertaken.
However, until such  technology  is  available  the  use  of  hot  water
recirculation  cannot be prohibited.  These systems perform an important
function at intake structures.  For this reason, the recommendation  for
ice  control  must  be qualified in a manner that does not prohibit this
system but encourages the development of alternate technology.

Technology - Ice Control at Intakes

The use of warm water recirculation for the purposes of controlling  ice
at  intake  structures should be limited to those installations where no
other means of ice control  are  available.   Where  such  a  system  is
employed, close control of the quantity of water recirculated and timing
of its use  (intermittent if possible) should be practiced.  The point of
application of the hot water should be located to minimize the potential
adverse  environmental  impact  that  can result from the application of
these systems.  The applicant is encouraged to seek alternate  solutions
to the ice control problem.  Intermittent operation of ice control could
prevent  fish  accumulations  which  might  occur  with a continuous ice
control.

Aesthetic Design

Where the intake structure and the  balance of the plant are separated by
great distances, the  intake structure can have an objectionable  physical
presence.  This will  be significant  in wilderness areas and   in  natural
and historic  preserves.  There are  various techniques available  to blend
the  intake   structure  with  its   surroundings.  The intake  may also be
lowered  to   reduce  its  impact.    However,  this   latter   approach  can
increase    costs  significantly  especially  where  rock  excavation  is
required.   Where the  plant and intake are located   close  together,  the
intake   will   be  dominated  by  the  plant  and  various   architectural
treatments   can  be   applied  to  create  an  attractive    grouping   of
structures.    This   latter factor is  another reason for locating intakes
close  to the  balance  of the plant.   Since aesthetic impacts are  governed
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by location conditions, a general measure for aesthetic  design  is  not
recommended.

Noise control

The  sound  level  of  large  circulating water pumps can be quite high.
Again this will be important only where the intake is  remotely  located
from the balance of the plant.  The noise level emanating from an intake
located  close to the plant will be dominated by the noise o± the plant.
Current practice, however, is to construct intakes, in milder  climates,
without  enclosures.   Where intake noise level is a factor, they should
be enclosed.  Enclosed intakes would not have significant sound  levels.
A uniform measure is  not recommended.

Construction

The  adverse  environmental  impact of the construction of cooling water
intake structures consists almost entirely of the effects of the aquatic
population  of  the  turbidity  increases   created   £>y   the   various
construction  activities.   The  U.S. Army Corps of Engineers already is
responsible for construction  in  navigable  waterways  and  all  intake
construction will have to conform to the corps' guidelines for dredging,
disposal of soil, etc.

Dredging, Excavation and Backfilling

These  activities  can  cause  significant  short  term increases in the
turbidity  of  the  source  water.   Depending  on  the  particle  size,
distribution of the excavated materials and the hydrology of the source,
the impact of the turbidity increase will be local or widespread.  It is
believed  that a two-fold approach for the control of turbidity increase
is required.  First an absolute limit should be placed on tne  level  of
turbidity  increase  resulting  from  these operations.  Second, typical
requirements, as follows, should be utilized to  reduce  the  impact  of
individual construction operations.

Technology  -  Turbidity Increase Resulting From Dredging Excavation and
Backfilling

The turbidity increase from construction  operations  on  cooling  water
intake  structures  should  not  exceed  a  specific  level  of  Jackson
turbidity units  (JTU)  set for  the  particular  site.   The  method  and
location  of the point of measurement should depend on the nature of the
aquatic community, the  length  of  the  construction  program  and  the
hydrology  of  the  receiving water.  This acceptable level of turbidity
should be based, as a  minimum, on existing water quality  standards  for
the classification of  the particular water body.
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Technology   -   Typical   Requirements  for  Dredging,  Excavation  and
Backfilling

- Excavation in low lying areas in the vicinity of the water
  body should be conducted with natural soil plugs or berms
  left in place.  When these soil plugs are removed, the one
  furthest away from the stream should te removed first.

- Where excavations are dewatered during construction, no
  discharge from the dewatering pump should be made to the
  waterbody unless it conforms to the turbidity standard set
  forth above; this may be require that the said discharges be
  settled or filtered prior to discharge.

- Materials excavated should be placed above the water line.
  Suitable slope protection for excavated materials should be
  provided.

- Underwater excavations for conduit should be scheduled to allow
  placing of the conduit and the closing of the excavation to be
  completed as rapidly as possible.  Backfill over conduit below
  the water line should be leveled to prevent sediment transport.

- Where large excavations and dredging operations are required
  it may be desirable to conduct these operations behind a re-
  taining structure such as an earth embankment or a coffer dam.
  Care must be taken in the construction and removal of these
  facilities so that the turbidity limits established above are
  not exceeded.

The  applicable  outline  specifications  contained  above   should   be
incorporated  in all intake construction where required.  The discharger
should indicate that these specifications shall be incorporated into the
contract documents for the construction of the intake.

Construction Scheduling

The construction of intakes can often be scheduled in a manner that  can
reduce  adverse  environmental  impact.   In  many waterbodies there are
significant water level variations during the year.  It may be  possible
to  schedule  much  of  the intake construction during low wat^r periods
when it can be done above water level.  In addition, construction should
be scheduled to avoid  spawning  seasons  and  migration  periods  where
turbidity increase can harm these functions.  The ability to schedule in
this  fashion  requires  that  the  appropriate  biological data be made
available.

Technology - Construction Scheduling

The scheduling of intake structure construction should take advantage of
low water periods to undertake certain construction work above the water
level.  Scheduling should also avoid kncwn periods of fish spawning  and
migration.
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Disposal of Spoil

The  disposal of spoil within navigable waters is controlled by the U.S.
Army Corps of Engineers.   In addition to any requirements that the Corps
establish, it is necessary to prevent the disposal  of  spoil  in  known
fish  spawning, feeding areas, shellfish beds and over important benthic
deposits.  The disposal of spoil in these areas can cause permanent loss
of important biological species.  In addition, spoil deposits both below
the water and above the water should be adequately stabilized to prevent
long term turbidity increases due to either water currents or erosion.

Technology - Disposal of Spoil

The disposal of spoil below the water line should be avoided.  In  those
cases  where  this cannot be avoided, spoil should not be disposed of in
spawning grounds, feeding areas and  over  important  bentnic  deposits.
All  spoil deposits should be adequately stabilized to prevent long term
ero si on.

Slope Protection for Excavation and Fills

The same considerations governing the stabilization  of  spoil  deposits
are  also applicable to the protection of slopes of excavation and fills
that are a permanent part of the intake.

Technology - Slope Protection for Intake Excavations and Fills

The slopes of all excavations  and  fills  incorporated  in  the  intake
structure shall be adequately protected against erosion and wave action.

Operation and^Maintenance

Although most of the environmental impact may occur during actual intake
operation,   it   will  not  be  possible  to  effect  intake  operation
significantly once it is placed in service.

Most of the control of adverse environmental impact of intake structures
would probably be obtained in the location and  design  criteria.   Some
degree  of  control over impingement effects might be achieved by proper
screen operational procedures.  Pump operation might also be  controlled
to  reduce environmental impact although the pumps are not a part of the
intake structure as strictly definad.  It would  also  be  desirable  to
develop   a  program  for  periodic  performance  monitoring  of  intake
structures.

Maintenance is not an aspect of intake  structure  operation  which  has
only  indirect  environmental  impact.   The discharger should submit in
outline form his  maintenance program for the intake system.
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Screen Operation

The impact of fish impingement on screens can be reduced  by  continuous
screen  operation to reduce the period of time that fish are impinged on
the screens.  This type of  operation to  reduce  impingement   effects
is only  applicable_ where fish separation and bypass    streams   are_
available.  Since the number of installations having this capability  is
small,  no  general  recommendations  or continuous screen operation are
made.  However, more of these systems may be installed  in  the  future.
Continuous  screen operation in this manner will shorten screen life and
increase maintenance costs.

Pump Operation

The ability to control pump operation can reduce impingement effects  at
certain  locations  during  the  winter months.  Pump flows often can be
reduced in the colder winter months with no detrimental effect on  plant
performance.   Since  fish  swimming  ability  is  reduced during colder
temperatures, such a flow reduction may  be  desirable  to  reduce  fish
impingement.  Since the pumps are not a part of the intake as previously
defined,   no  measures  regarding  pump  performance  are  recommended.
However, pump controls may be desirable in certain locations.

Performance Monitoring

A program  of  performance  monitoring  of  intakes  is  recommended  to
establish data on the performance of these systems.

Technology  - Performance Monitoring of Intake  Structures

The   performance  of  intakes should be monitored on a continuing basis.
The  owners  of  intake structures  should periodically  submit  performance
data that consisting of the following:

-  Source  water temperatures
-  Stream  flows  (if  applicable)
-  Screen  operation  schedule
-  Cooling water  flow
-  Number, types,  and condition of important organisms
   impinged,  entrained,  and bypassed.

Applicability  of  Intake Structure Technology

For   new  sources,  no measure  other  than  proper location  of  the  intake in
correspondence iwth the intake volumes  required  should  be relied upon.

 In many cases  an  existing establishment  may have reason  to   replace  the
 nonrecirculating   cooling  water   system  with   an  essentially  closed
 recirculating   system.    The   reduction   in  intake  water   quantity  by
 installing  the closed  cooling system should significantly reduce adverse
 environmental   impact  resulting  from the cooling para like  water intake.
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Furthermore, intake flow could be reduced during certain time periods to
minimize adverse environmental impact.

A stepwise approach to intake modifications is generally recommended for
cases where adverse environmental impact must be reduced by this means:

The  first  step  should  be  to  attempt  to  reduce  impact   by   the
modifications   of   the   existing  screening  systems.   The  possible
modifications that can be applied are discussed in the design section of
this report.  The performance of this type of modification has not  been
fully   documented  because  initial  installation  is  presently  under
construction.  However, the cost of in-place modifications of this  type
are  not  excessive  and  they  can generally be made while the plant is
operating.

The second step should be to increase the size of the intake  to  reduce
high  approach velocities.  This will require additional screen and pump
bays and most likely the replacement of the existing pumps to reduce the
flow through each bay.  This type of modification  could  also  be  done
while  the structure is kept in service but only where extra screen bays
are available.

The third step should be to abandon the existing intake and  replace  it
with   a  new  intake  at  a  different  location  and  incorporting  an
appropriate design.  This  could  be  very  costly  particularly  if  an
offshore  inlet is required.  The recommendation of such a change should
be very carefully considered.   However,  a  particular  discharger  may
elect to avoid the costs and uncertainties associated with the fixst two
steps and proceed directly to step three.

The  time  required  for  the  installation  of these changes at a steam
electric powerplant, for example, will vary from as low  as  3-4  months
for the modification of an individual screen bay to as much as two years
to completely construct a new intake.

Cost of Implementation of Intake Structure Technology

The  cost of the implementation of the required technology can vary from
intake to intake.   The costs  associated  with  implementation  will  be
mainly  due  to the capital costs of the facilities proposed.   Operation
and maintenance costs are relatively small for existing intakes and  the
technology will not increase these costs significantly.

New Intakes

The  cost  of intake structures at powerplants is presently estimated to
be between $3 and $20 (between 2 and 10%  of  present  plant  cost)   per
kilowatt  of  installed  capacity,   the  lower  range  being  for larger
circulation water intakes of the shoreline type.   The  higher   range  is
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for  intakes  for  smaller service water systems which require extensive
offshore piping.

The potentially  major  cost-impacting  measures  would  be  those  that
require  a  reduced  approach  velocity  ;and  the requirement for flush
mounting screens.  The implementation of these  measures  might  add  as
much  as  70%  to  the cost of a tankside intake.  For a powerplant this
would be equivalent to between $2  and  $4  per  kilowatt  of  installed
capacity.   Installing an offshore intake reather than a bankside intake
can add considerably more to the cost.

Existing Intakes

The cost impact to existing sources can be considerably greater than  to
new  sources.   In  the  worst  case,  where  an  entirely new intake is
required which requires extensive offshore conduit, the cost  should  be
as  great as the $20 per kilowatt stated above.  The impact of this cost
on an older plant will generally be more severe than on a  newer  plant.
Since  these  changes  cannot be entirely relied upon to actually reduce
adverse environmental impact in any case, these modifications should  be
carefully considered before implementation.
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                              SECTION VIII

                            ACKNOWLEDGEMENTS


The  development  of this report was accomplished through the efforts of
Burns and Roe, Inc.   The following Burns and Roe, Inc., technical  staff
members made significant contributions to this effort:

    Henry Gitterman, Director of Engineering
    John L.  Rose, Chief Environmental Engineer
    Arnold S. Vernick, Project Manager
    William A. Foy,  Senior Environmental Engineer
    Richard T. Richards, Supervising Civil Engineer

The  actual  preparation  of  this document was accomplished through the
efforts of the secretarial and  other  non-technical  staff  members  at
Burns  and Roe, Inc., and the Effluent Guidelines Division.  Significant
contributions were made by the following individuals:

    Ms. Sharon Ashe, Effluent Guidelines Division
    Ms. Brenda Holmone, Effluent Guidelines Division
    Ms. Chris Miller, Effluent Guidelines Division
    Ms. Marilyn Moran, Burns and Roe, Inc.
    Ms. Kaye Starr,  Effluent Guidelines Division
    Mr. Edwin L. Stenius, Burns and Roe, Inc.

The contributions of Ernst P. Hall, Deputy Director, Effluent Guidelines
Division, and C. Ronald McSwiney,  Effluent  Guidelines  Division,  were
vital  to  the timely publication of this report.  Ms.  Kir Krickenberger
and Dr. Chester Rhines of the Effluent Guidelines Division also assisted
in the preparation of rhis report.

The members of the working group/steering committee, who coordinated the
internal EPA review, in addition to Mr. Cywin and Dr. Nichols are:

    Walter J. Hunt,  Chief, Effluent Guidelines Development Branch, EGD
    Dr. Clark Allen, Region VI
    Alden G. Christiansen, National Environmental Research
      Center, Corvallis
    Swepe Davis, Office of Planning and Management
    Don Goodwin, Office of Air Quality Planning and Standards
    William Jordan,  Office of Enforcement and General counsel
    Charles Kaplan,  Region IV
    Steve Levy, office of Solid Waste Management Programs
    Harvey Lunenfeld, Region II
    George Manning,  Office of Research and Development
    Taylor Miller, Office of General Counsel
    James Shaw, Region VIII
    James Speyer, Office of Planning and Management
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    Howard Zar,  Region V

Other EPA and State Personnel contributing to this effort are:

    Allan Abramson, Region IX
    Ken Bigos, Region IX
    Carl W.  Blomgren, Region VII
    Danforth G.  Bodien, Region X
    Richard Burkhalter, State of Washington
    Gerald P. Calkins, State of Washington
    Robert Chase,  Region I
    William Dierksheide, Region IX
    William Eng, Region I
    James M. Gruhlke, Office of Radiation Programs
    William R. Lahs, Office of Radiation Programs
    Don Myers, Region V
    Dr. Guy R. Nelson, National Environmental Research Center,
      Corvallis
    Courtney Riordan, Office of Technical Analysis
    William H. Schremp, Region III
    Edward Stigall, Region VII
    Dr. Bruce A. Tichener, National Environmental Research
      Center, Corvallis
    Srini Vasan, Region V

Other Federal agencies cooperating are:

    Atomic Energy Commission
    National Marine Fisheries Service, National Oceanographic
      and Atmospheric Administration, Department of Commerce
    Bureau of Reclamation, Department of the Interior
    Bureau of Sport Fish and Wildlife, Department of the Interior
    Tennessee Valley Authority

The Environmental Protection Agency also  wishes  to  thank  the  repre-
sentatives  of  the  steam  electric  generating industry, including the
Edison Electric Institute, the American Public Power Association and the
following utilities and  regional  systems  for  their  cooperation  and
assistance   in   arranging   plant   visits  and  furnishing  data  and
information.

    Alabama Power Company
    Canal Electric Company
    Central Hudson Gas & Electric Corporation
    Commonwealth Edison Company
    Consolidated Edison Company of New York, Inc.
    Consumers Power Company
    Duke Power Company
    Florida Power & Light Company
    Fremont, Nebraska Department of Utilities
                                   160

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    MAPP Coordination center for the Mid-Ccntinent
      Area Power Systems
    New England Power company
    New York Power Pool
    New York State Electric & Gas Corporation
    Niagara Mohawk Power corporation
    Omaha Public Power District
    Pacific Gas & Electric company
    Pacific Power & Light Company
    Pennsylvania Power & Light Company
    Portland General Electric Company
    Potomac Electric Power company
    Public Service Company of Colorado
    Public Service Electric & Gas company
    Sacramento Municipal Utility District
    Southern California Edison company
    Taunton, Massachusetts Municipal Light Plant
    Texas Electric Service company
    Virginia Electric & Power Company

Acknowledgement is also made to the following  manufacgurers  for  their
willing  cooperation  in  providing  information needed in tne course of
this effort.

    Beloit-Passavant
    F. W. Brackett & Company, Ltd.
    J. Blakeborough & Sons, Ltd.
    Link Belt Company
    R. E. Reimund Company
    Rexnord, Inc.
    Stephens-Adamson
                                   161

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                               SECTION IX

                               KEFERENCES
1.  Bates, D.W.,  Diversion, and Collection of Juvenile Fish wirh
    Traveling Screens, U.S. Department of the Interior, Fishery
    Leaflet 633,  (March 1970).

2.  Beall, S. E.,  Us§_s_of_Waste_Heat, research sponsored by
    the U.S. AEC under contract with the Union Carbide
    Corporation,  (November 3,  1969).

3.  "Director", Public Power,  Vol. 31, No. 1, (January -
    February 1973).

4.  "Dive Into Those Intakes", Electric_Lic[ht_&_Power, E/G
    edition, pp.  52-53, (November 1972) .

5.  Electric Power .Statistics, Federal Power Commission,
    (January 1972).

6.  Electrical World^ Directgry_of_Electric Utilities, McGraw-Hill
    Inc., New York, 31st Edition,  (1972-1973).

7.  Environmental  Effects of Producing Electric Power Hearings
    before the Joint Committee on Atomic Energy 91st congress,
    Second Session, Parts 1 and 2, Vol. I & II, (October, November
    1969 and January and February 1970).

8•  Final Environmental Statement, USAEC, Directorate of Licensing:

    a)    Arkansas  Nuclear One  Unit 1
         Arkansas  Power & Light Co., (February 1973).

    b)    Arkansas  Nuclear One  Unit 2
         Arkansas  Power & Light Co., (September 1972).

    c)    Davis-Bessee Nuclear  Power Station
         Toledo Edison company 6 Cleveland Electric
         Illuminating Company, (March 1973).

    d)    Duane Arnold Energy Center
         Iowa Electric Light & Power Company
         Central  Iowa Power Cooperative
         Corn Belt Power Cooperative,  (March 1973) .

    e)    Enrico Fermi Atomic Power Plant Unit 2
                                163

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     Detroit Edison Company, (July 1972).

f)    Fort Calhoun Station Unit 1
     Omaha Public Power District,  (August 1972).

g)    Indian Point Nuclear Generating Plant UNit No. 2
     Consolidated Edison Co. of New York, Inc., Vol. 1
     (September 1972).

h)    Indian Point Nuclear Generation Plant Unit No. 2
     Consolidated Edison Co. Of New York, Inc. Vol. II

i)    James A. Fitzpartrick Nuclear Power Plant
     Power Aurthority of the State of New York,
     (March 1973).

j)    Joseph M. Farely Nuclear Plant Units 1 and 2
     Alabama Power Company,  (June  1972).

k)    Kewaunee Nuclear Power Plant
     Wisconsin Public Service Corporation,
     (December 1972).

1)    Maine Yankee Atomic Power Station
     Maine Yankee Atomic Fewer Company,  (July  1972) .

m)    Oconee Nuclear  Station Units  1, 2  and 3
     Duke Power company,  (March 1972).

n)    Palisades Nuclear Generating  Plant
     Consumers Power Company,  (June 1972).

o)    Pilgrim Nuclear Power Station
     Boston Edison Company,  (May 1972).

p)    Point Beach Nuclear Plant Units 1  and 2
     Wisconsin Electric Power Co.  and
     Wisconsin Michigan Power Company,  (May 1972).

q)    Quad-Cities Nuclear Power Station  Units  1 and  2
     Commonwealth Edison Company and the
     Iowa-Illinois Gas and Electric Company,
      (September  1972) .

r)    Rancho Seco Nuclear Generating Station Unit  1
     Sacramento Municipal Utility  District,  (March  1973)

s)    Salem Nuclear Generating Station  Units 1 and 2
     Public Service  Gas & Electric Company,  (April  1973)
                              164

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    t)    Surry Power Station Unit 1
         Virginia Electric and Power Co., (May 1972).

    u)    Surry Power Station Unit 2
         Virginia Electric & Power Co. (June 1972).

    v)    The Edwin I.  Hatch Nuclear Plant Unit 1 and 2
         Georgia Power company, (October 1972).

    w)    The Fort St.  Vrain Nuclear Generating Station
         Public Service company of Colorado, (August 1972) .

    x)    Three Mile Island Nuclear Station Units 1 and 2
         Metropolitan Edison Company, Pennsylvania Electric
         Company and,  Jersey Central Power and Light Co.,
         (December 1972).

    y)    Turkey Point Plant
         Florida Power and Light Co., (July 1972).

    z)    Vermont Yankee Nuclear Power Station
         Vermont Yankee Nuclear Power Corporation, (July 1972).

   aa)    Virgil C. Summer Nuclear Station Unit 1
         South Carolina Electric £ Gas Company, (January 1973) .

   bb)    William B. McGuire Nuclear Station Units 1 and 2
         Duke Power company, (October 1972).

   cc)    Zion Nuclear Power Station Units 1 and 2
         Commonwealth Edison Company, (December 1972).

9.   Garton,  R. G. and Harkins, R. D., Guidelines: Biological
    Surveygmat Proposed Heat Discharge Sites EPA Water Quality
    Office,  Northwest Region.   (April 1970).

10. Hirayama, K., and Hirano, R., "Influence of High Temperature
    and Residual Chlorine on Marine Phytoplankton".

11. Intake Systems for Desalting Plants, U.S. Department of
    Interior, Office of Saline Water, Research and Development
    Progress Report No. 678, (April 1971) .

12. Jenson,  L.D. and Brady, O.K., "Aquatic Erosystems and
    Thermal  Power Plants".  Proceedings of the ASCE,
    (January 1971) .

13. Maxwell, W.A., Fish Diversion for Electrical Generating
    Station  Coolinc Systems - A State^of the Art Report, for
    Florida  Power & Light Co.,  (March 1973) .
                                165

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14.  Mayo, R.D.  and James W.T., "Rational Approach to the Design
    of Power Plant Intake Fish Screens using both Physical
    and Behavioral Screening Methods", Technical Reprint
    No. 15,  Kramer, Chin & Mayo, (September 1972).

15.  Metric^Practice Guide, (A Guide to the Use of Si - the Inter-
    national System of Units), American Society for Testing and
    Materials,  Philadelphia, Pennsylvania.

16  Peterson, D.E., Sonnichsen, Jr., et al, "Thermal Capacity
    of Our Nation's Waterways", ASCE Annual & National
    Environmental Engineering Meeting,  (October 1972).

17.  Report on Best Intake Technology Available for Lake
    Michigan, Preliminary Draft, by Ccoling Water Intake
    Technical Committee,  (May 1973).

18.  Richards, R.T., "Fish Protection at Circulating Water Intake",
    Burns and Roe, Inc., unpublished research paper. May 11, 1967.

19.  Richards, R.T. , Intake for the Makeup Water Pumping System
    WPPSS tjuclear Project No., 2 prepared for Washington Public
    Power Supply System,  (March 1973).

20.  Richards, R.T. , "Intake for the Makeup Water Pumping System,
    Hanford No. 2", Burns and Roe, Inc.,  (January 1973).

21.  Riesbal, H.S. and Gear, R.J.L., "Application of Mechanical Systems
    to Alleviation of Intake Entrapment Problems", presented at the
    Atomic Industrial Forum, Conference on Water Quality Considerations,
    Washington, D.C., (October 2, 1972).

22.  Schreiber,  D.L., et al, Appraisal of Water Intake Systems
    on the Central CQlumbia_River to Washington Public Power
    Supply~System (March 1973).

23.  Skrotzki, E.G.A. and Vopat, W.A., Power Station Engineering
    and Economy,  McGraw Hill Book Co., N.Y. (1960).

24.  Sonnichsen, Jr., J.C., Bentley, B.W., et al, A Review of
    Thermal Power Plant Intake Structure Designs and Related
    Environmental Considerations prepared for the U.S. Atomic
    Energy Commission, Division of Reactor Development and
    Technology.

25.  Statistics of Privately Owned Electric .Utilities of the U.S. -
    1970, Federal Power Commission,  (December 1971).
                              166

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26.  Statistics of^Publicly^Owned,Electric ^Utilities of_the U.S. -
    1970,  Federal Power commission,  (February 1972).

27.  steanL^^c^ric_PlantA_Air_and_Viater_fiualitx_Controlf Summary
    Report,  Federal Power Commission,  (December 1969).

28.  ^t^gni_Kl_££h£ic_Plant_Construction Cost and Annual Production
    Expenses, Twenty-Second Annual Supplement, Federal Power
    Commission,  (1969).

29.  The_Electricity_Su£p.ly_Industry., 22nd Inquiry, The
    Organization for Economic Co-operation and Development  (1972).

30.  Bibko, P., et al, "Effects of Light and Bubbles on tne Screening
    Behavior of the Striped Bass", westinghcuse Environmental
    Systems, paper presented at the  Entrainment and Intake
    Screening Workshop, ;the Jchn Hopkins University,
    (February 8, 1973) .

31.  Skinner, J.E., California Department of Fish and  Game,
    "Evaluation of Large Functional  Louver Screening  Systems
    and Fish Facilities, Research on California Water
    Diversion Projects", paper presented at the Entrainment
    and Intake Workshop, the John Hopkins University,
    (February 8, 1973) .

32.  Schuler, V.J. and Larson, L.E.,  Ichthyological Associates
    and Southern California Edison Company, Fish Guidance and
    Louver Systems at Pacific Ccast  Intake Systems",  paper
    presented at the Entrainment and Intake Workshop, The
    John Hopkins University,  (February  8, 1973) .

33. Beloit-Passavant_CorporatiQn_Bulletin_1100

34. Engineering^!:or Resolution of the  Energy  - Environment Dilemma,
    Committee on Power Plant Siting, National Academy of
    Engineering, Washington, D.C.,  (1972).
                                  167

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                               SECTION X


                                GLCSSAEY


Agglomeration

The coalescence of dispersed  suspended  matter  into  larger  floes  or
particles which settle more rapidly.

Brackish Water

Water  having a dissolved solids content between that of fresh water and
that of sea water, generally from 1000 to 10,000 mg per liter.

Brine

Water saturated with a salt.

CFM

Cubic foot  (feet) per minute.

Circulating Water_Pumps

Pumps which deliver cooling water to the condensers of a powerplant.

Circulating__Water_ System

A  system which conveys  cooling  water  from   its  source   to  the  main
condensers  and then to the point of discharge.  Synonymous with  cooling
water system.

Closed Circulating Water System

A  system which passes water through the  condensers,  then through   an
artificial  cooling device, and keeps recycling it.

Cooling Canal

A  canal in  which  warm water enters  at one end, is  cooled by contact with
air, and is discharged at the other end.

Cooling^ Lake

See Cooling Pond.
                                169

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Cooling Pond

A  body  of water in wnich warm water is cooled by contact with air, and
is either discharged cr returned for reuse.

Cooling Tower
A h^t exchange device which  transfers  reject  heat  from  circulating
water to the atmosphere.

Cooling Water System

See Circulating Water System.

Crib

A type of inlet structure.

Critical Aguatic Organisms

Aquatic organisms that are commercially or recreationally valuable, rare
or  endangered,  of  specific  scientific  interest, or necessary to the
well-being of  some  significant  species  or  to  the  balance  of  the
ecological system.

Curtain Wall

A  vertical  wall  at  the  entrance  to  a  screen  or intake structure
extending from above, to some pcint below, the water surface.
To release or vent.

Discharge Pipe or Conduit

A section of pipe or conduit from the condenser discharge to  the  point
of discharge into receiving waters or cooling device.

Entrair.ment

The  drawing  along  of  organisms due to the mass motion of the cooling
water.

Entrapment

The prevention of the escape of  organisms  due  to  the  cooling  water
currents and forces involved.
                                 170

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Fiiter_Bed

A  device  for  removing  suspended  sclids  from  water,  consisting of
granular material placed in  horizontal  layers  and  capable  of  being
cleaned hydraulically by reversing the direction of the flow.

Filtration

The  process  of  passing  a  liquid  through a filtering medium for the
removal of suspended or colloidal matter.

Fixed or Stationary Screen

A nonmoving fine mesh screen which must be lifted out  of  the  waterway
for cleaning.

Floe

Small  gelatinous  masses  formed  in  a  liquid  by  the  reaction of a
coagulant   added   thereto,   thru   biochemical   processes,   or   by
agglomeration.

FPS

Foot  (feet) per second

Foot  (feet) - Designated as  11, 21 , etc.

Impingement

Sharp  collision  of  organism  with  a  physical  member  of the intake
structure.

ID

Inside diameter

Inch	(inches)

Designated as  1", 2", etc.

Infiltration  Bed

A device  for  removing suspended solids  from  water consisting of  natural
deposits  of  granular material under which a system of  pipes collect the
water after passage through  the bed.

Inlet Pipe or Conduit

See Intake Pipe or Conduit.
                                  171

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Intake_Pi2§_2£_ conduit

A section of pipe or conduit from the pump discharge  to  tne  condenser
inlet;  also  used for the pipe leading from the inlet to the screens or
pumps.

Intake or_Intak,e_Structure

A structure containing inlet, water cleaning facilities and/or pumps.

KN

Kilo Newton

MPS

Meters per second.


Makeup Water_Pump_s

Pumps which provide water to replace that lost by evaporation,  seepage,
and blowdown.

Mine-mouth_Plant

A  steam  electric  powerplant located within a short distance of a coal
mine and to which the coal is transported from the mine  by  a  conveyor
system, slurry pipeline or truck.

M3

Cubic Meter

Nominal Capacity

Name plate - design rating of a plant, or specific piece of equipment.

Once-through Circulating Water System

A  circulating  water  system  which  draws water from a natural source,
passes it through the main condensers and returns it to a  natural  body
of water.

Powerplant

Equipment  that produces electrical energy, generally be conversion from
heat energy produced by chemical or nuclear reaction.

Pump and_Screen_Structure

A  structure  containing pumps and  facilities   for  removing   debris   from
water.
                                    172

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Pump Chamber

A  compartment  of  the intake or pump and screen structure in which the
pumps are located.

Pump Runout

The tendency of a centrifugal pump to deliver more than its design  flow
when the system resistance falls below the design head.

PVC

Polyvinylchloride

Recirculation System

Facilities  which  are specifically designed to divert the major portion
of the cooling water discharge back to the cooling water intake.

Recirculation

Return of cooling water discharge back to the cooling water intake.

Salin e_ Water

Water containing salts.

Second

Abbreviation = s

Sampling, Stations

Locations where several flow samples are tapped for analysis.

Screen Chamber

A compartment of the intake of pump and screen structure  in  which  the
screens are located.

Screen Structure

A structure containing screens for removing debris from water.

Sedimentation

The  process of subsidence and deposition of suspended matter carried by
a liquid.
                                 173

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Service Water Pumps


Pumps providing water for auxiliary  plant  heat  exchangers  ana  other
uses.

Station

A plant comprising one or several units for the generation of power.

Stop Logs

A  device  inserted  in  guides  at the entrance to a waterway to permit
dewatering.  It can be made up  of  individual  timber  logs,  but  more
commonly of panels of steel, timber, or timber and concrete.

Total Dynamic Head	ITDH]_

Total  energy  provided  by  a  pump  consisting  of  the  difterence in
elevation between the suction and discharge levels, plus losses  due  to
unrecovered velocity heads and friction.

Tgg§h_Ragk^ Trash gars. Grizzlies

A grid, coarse screen or heavy vertical bars placed across a water inlet
to catch floating debris.

Trash Rake

A mechanism used to clean the trash rack.

Traveling^Screen

A  device  consisting  of  a  continuous  band  of  vertically or nearly
vertically revolving screen elements placed at right angles  to tne water
flow.  Screen elements are cleaned automatically  at  the  tope  of  the
revolution.

Turbidity

Presence  of  suspended  matter   such   as organic or inorganic material,
plankton or other microscopic organisms which reduce the clarity of  the
water.

Unit

In   steam  electric  generation,   the   basic system for power generation
consisting of a  boiler and  its associated turbine and generator  with the
required auxiliary equipment.
                                  174

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Utili-t-y

(Public utility)  a company,  either  investor-owned  or  publicly  owned
which provides service to the public in general.  The electric utilities
generate and distribute electric power.

Velocity Cap, Fish Cap

A  horizontal plate placed over a vertical inlet pipe to cause flow into
the pipe inlet to be horizontal rather than vertical.

Wet Well

A compartment of the pump structure in which the liquid is collected and
to which the pump suction is connected.
                                 175

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